JP2018059983A - Display device, display module, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device that has power consumption reduced by increasing a viewing angle.SOLUTION: A display device has a first display area on a first face, a second display area on a second face, and a third display area on a third face. A cabinet has a hinge for fixing the first face and the third face in different directions. The display area has a pixel; the pixel has a first display element and a second display element; the first display element has a reflection electrode for reflecting visible light; the reflection electrode has an opening region and allows visible light from the second display element to pass through for displaying. The second display element has a first region with the same area as that of the opening region, and a second region with a larger area than that of the opening region; the second region has a range of overlapping fields of view by increasing a first viewing angle of the second display element of the first face and a second viewing angle of the second display element of the third face.SELECTED DRAWING: Figure 1

Description

  One embodiment of the present invention relates to a display device, a display module, and an electronic device.

  Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Or this invention relates to a process, a machine, a manufacture, or a composition (composition of matter). In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, a driving method thereof, or a manufacturing method thereof.

  Note that in this specification and the like, a semiconductor device refers to an element, a circuit, a device, or the like that can function by utilizing semiconductor characteristics. As an example, a semiconductor device such as a transistor or a diode is a semiconductor device. As another example, the circuit including a semiconductor element is a semiconductor device. As another example, a device including a circuit including a semiconductor element is a semiconductor device.

  Mobile devices such as smartphones, tablets, and electronic books are widespread. Mobile devices are required to display suitable for the brightness of the environment used such as the outdoor environment and indoor environment. Furthermore, when reading an electronic book with an electronic book, a tablet, etc., it is required that it can be used for a long time.

  Low power consumption is achieved by displaying using reflected light in environments where there is sufficient external light, such as natural light or indoor lighting, and using light emitting elements in environments where sufficient brightness cannot be obtained. There has been proposed a display device that realizes the realization.

  For example, Patent Document 1 discloses a hybrid (composite type) display device in which a pixel circuit for controlling a liquid crystal element and a pixel circuit for controlling a light emitting element are provided in one pixel.

  For example, Patent Document 2 discloses that a display of a specific area is selectively updated by a decoder circuit in order to reduce power consumption of a mobile device.

  The OS transistor has a very small off-state current. A technique for reducing the power consumption of a liquid crystal display or an organic EL display by utilizing this fact and reducing the refresh frequency when displaying a still image is disclosed in Patent Document 3. In the present specification, the technique for reducing the power consumption of the display device described above is referred to as idling stop driving.

International Publication No. 2007/041150 JP 2011-085918 A JP 2011-141522 A

  As a method for performing display using external light, there is a reflective liquid crystal display device. A reflective liquid crystal display device does not require a backlight and thus consumes low power. However, good display cannot be achieved unless the place is where bright outside light can be obtained. Since the EL (Electroluminescence) element is a self-luminous element, the light-emitting display device can perform good display in a dark place. On the other hand, the brightness is fixed with respect to outside light in a bright place. There are challenges.

  Smartphones, tablets, electronic books, personal computers, and the like are often used in places where bright external light can be obtained. Among them, a mobile device used in a place where bright external light can be obtained, such as a smartphone and a tablet, is displayed with high luminance in order to improve visibility. Therefore, it is easy to consume electric power. Therefore, it is necessary to increase the capacity of the battery so that it can be used for a long time. However, when the capacity of the battery is increased, there is a problem that the mobile device becomes heavy.

  When using a smartphone, a tablet, an electronic book, or the like for a long time, it is necessary to reduce power consumption. As typical methods for controlling power consumption, there are control methods such as power gating and clock gating. In the case of a display device, methods such as reducing the number of display updates have been proposed. However, when the display update interval becomes longer, charge leakage occurs in the switch transistor that holds data. There is a problem in that the visibility is lowered because data held by charge leakage deteriorates and flickers.

  In addition, with the diversification of display information, a folding game machine and an electronic device including a flexible display having flexibility have been developed. However, the folding game machine employs at least two different display areas. Further, an electronic device including a flexible display has a curved surface, and thus the display direction is not limited to one. When two or curved display areas are handled as one display area, there is a problem in visibility because the display angles are different. Furthermore, in order to control the two display areas, there is a problem that the number of components such as an IC increases.

  In view of the above problems, an object of one embodiment of the present invention is to provide a display device with a novel structure. Another object of one embodiment of the present invention is to provide a display device that improves display visibility. Another object of one embodiment of the present invention is to provide an electronic device that reduces power consumption.

  Note that the description of these problems does not disturb the existence of other problems. Note that one embodiment of the present invention does not have to solve all of these problems. Issues other than these will be apparent from the description of the specification, drawings, claims, etc., and other issues can be extracted from the descriptions of the specification, drawings, claims, etc. It is.

  Note that the problems of one embodiment of the present invention are not limited to the problems listed above. The problems listed above do not disturb the existence of other problems. Other issues are issues not mentioned in this section, which are described in the following description. Problems not mentioned in this item can be derived from descriptions of the specification or drawings by those skilled in the art, and can be appropriately extracted from these descriptions. Note that one embodiment of the present invention solves at least one of the above-described description and / or other problems.

  One embodiment of the present invention includes a first surface, a second surface, and a third surface, and the first surface and the third surface are continuous through the second surface. The second surface having the curvature is provided between the first surface and the third surface, the first surface has the first display area, and the second surface Has a second display area, the third surface has a third display area, and the fourth display area is configured by using the first display area and the second display area. The fifth display area is configured using the second display area and the third display area, and the sixth display area is configured using the first display area, the second display area, and the third display area. A display device is characterized by constituting a region.

  In each of the above structures, the first display area, the second display area, and the third display area have a plurality of pixels, and the pixels include the first display element and the second display element. The first display element has a reflective electrode for reflecting visible light included in external light, the reflective electrode has an opening region or a notch region, and the second display element Has a function of transmitting visible light from an opening region or a notch region, and the first display element and the second display element are preferably a display device having a function of displaying different gradations. .

  In each of the above configurations, the first viewing angle on the first surface and the second viewing angle on the third surface, and a region where the first viewing angle and the second viewing angle overlap. The characteristic display device is preferred.

In each of the above configurations, the second display element includes a first region having the same area as the opening region or the notch region, and a second region having a larger area than the opening region or the notch region. Have
The second area has a function of widening the viewing angle of the second display element in the first display area and the viewing angle of the second display element in the third display area. The display device is preferably characterized in that the viewing angle of the second display element in the region overlaps the viewing angle of the second display element in the third display region.

  In each of the above structures, in each of the first display area and the third display area, the second display element includes a first area that overlaps the opening area or the notch area and a first area that does not overlap the opening area or the notch area. Preferably, the display device is characterized in that the area of the second region in the first display region is different from the area of the second region in the third display region.

  In each of the above structures, a display device in which the first display element is a reflective liquid crystal element is preferable.

  In each of the above structures, the second display element is preferably a display device that is a light-emitting element.

  The display device having any one of the above structures preferably includes a transistor, and the transistor is preferably a display device including a metal oxide in a semiconductor layer.

  In each of the above structures, the display device is preferably characterized in that the transistor has a back gate.

  In each of the above structures, a display device having a function of displaying an image by one or both of the first light reflected by the first display element and the second light emitted by the second display element. preferable.

  A display module including any one of the above-described display devices and a touch sensor is preferable.

  An electronic device including any one of the above-described display devices or display modules, a CPU, and a battery is preferable.

  One embodiment of the present invention can provide a display device having a novel structure. Alternatively, according to one embodiment of the present invention, a display device that can improve display visibility can be provided. Alternatively, according to one embodiment of the present invention, an electronic device that reduces power consumption can be provided.

  Note that the effects of one embodiment of the present invention are not limited to the effects listed above. The effects listed above do not preclude the existence of other effects. The other effects are effects not mentioned in this item described in the following description. Effects not mentioned in this item can be derived from the description of the specification or drawings by those skilled in the art, and can be appropriately extracted from these descriptions. Note that one embodiment of the present invention has at least one of the above effects and / or other effects. Accordingly, one embodiment of the present invention may not have the above-described effects depending on circumstances.

(A) The side view of an electronic device. (B) A cross-sectional view illustrating a structure of a display device. Sectional drawing of a display apparatus. FIG. Configuration example of an electronic device. FIG. 10 is a circuit diagram illustrating a pixel. FIG. 9 illustrates a structure of a pixel. FIG. 10 is a cross-sectional view illustrating a structure of a pixel. 3A and 3B illustrate a structure of a transistor. FIG. 5A illustrates a structure of a display device. FIG. 5B is a diagram illustrating an example of a display module. (A) Configuration example of navigation system. (B) A block diagram of the navigation system. A table describing the display mode. flowchart. The figure explaining the measurement result of the XRD spectrum of a sample. The figure explaining the TEM image of a sample, and an electron beam diffraction pattern. The figure explaining the EDX mapping of a sample. 8A and 8B illustrate a structural example of an electronic device.

  Hereinafter, embodiments will be described with reference to the drawings. However, the embodiments can be implemented in many different modes, and it is easily understood by those skilled in the art that the modes and details can be variously changed without departing from the spirit and scope thereof. . Therefore, the present invention should not be construed as being limited to the description of the following embodiments.

  In the drawings, the size, the layer thickness, or the region is exaggerated for simplicity in some cases. Therefore, it is not necessarily limited to the scale. The drawings schematically show an ideal example, and are not limited to the shapes or values shown in the drawings.

  In addition, the ordinal numbers “first”, “second”, and “third” used in the present specification are attached to avoid confusion between components, and are not limited numerically. Appendices.

  In addition, in this specification, terms indicating arrangement such as “above” and “below” are used for convenience to describe the positional relationship between components with reference to the drawings. Moreover, the positional relationship between components changes suitably according to the direction which draws each structure. Therefore, the present invention is not limited to the words and phrases described in the specification, and can be appropriately rephrased depending on the situation.

  In this specification and the like, a transistor is an element having at least three terminals including a gate, a drain, and a source. A channel region is provided between the drain (drain terminal, drain region or drain electrode) and the source (source terminal, source region or source electrode), and a current flows through the drain, channel region, and source. It is something that can be done. Note that in this specification and the like, a channel region refers to a region through which a current mainly flows.

  In addition, the functions of the source and drain may be switched when transistors having different polarities are employed or when the direction of current changes during circuit operation. Therefore, in this specification and the like, the terms source and drain can be used interchangeably.

  In addition, in this specification and the like, “electrically connected” includes a case of being connected via “thing having some electric action”. Here, the “thing having some electric action” is not particularly limited as long as it can exchange electric signals between connection targets. For example, “thing having some electric action” includes electrodes, wiring, switching elements such as transistors, resistance elements, inductors, capacitors, and other elements having various functions.

  Further, in this specification and the like, “parallel” means a state in which two straight lines are arranged at an angle of −10 ° to 10 °. Therefore, the case of −5 ° to 5 ° is also included. “Vertical” refers to a state in which two straight lines are arranged at an angle of 80 ° to 100 °. Therefore, the case of 85 ° to 95 ° is also included.

  In this specification and the like, the terms “film” and “layer” can be interchanged with each other. For example, the term “conductive layer” may be changed to the term “conductive film”. Alternatively, for example, the term “insulating film” may be changed to the term “insulating layer”.

  In this specification and the like, unless otherwise specified, off-state current refers to drain current when a transistor is off (also referred to as a non-conduction state or a cutoff state). The off state is a state where the voltage Vgs between the gate and the source is lower than the threshold voltage Vth in the n-channel transistor, and the voltage Vgs between the gate and the source in the p-channel transistor unless otherwise specified. Is higher than the threshold voltage Vth. For example, the off-state current of an n-channel transistor sometimes refers to a drain current when the voltage Vgs between the gate and the source is lower than the threshold voltage Vth.

  The off-state current of the transistor may depend on Vgs. Therefore, the off-state current of the transistor being I or less sometimes means that there exists a value of Vgs at which the off-state current of the transistor is I or less. The off-state current of a transistor may refer to an off-state current in an off state at a predetermined Vgs, an off state in a Vgs within a predetermined range, or an off state in Vgs at which a sufficiently reduced off current is obtained.

As an example, when the threshold voltage Vth is 0.5 V, the drain current when Vgs is 0.5 V is 1 × 10 ⁻⁹ A, and the drain current when Vgs is 0.1 V is 1 × 10 ⁻¹³ A. Assume that the n-channel transistor has a drain current of 1 × 10 ⁻¹⁹ A when Vgs is −0.5 V and a drain current of 1 × 10 ⁻²² A when Vgs is −0.8 V. Since the drain current of the transistor is 1 × 10 ⁻¹⁹ A or less when Vgs is −0.5 V or Vgs is in the range of −0.5 V to −0.8 V, the off-state current of the transistor is 1 It may be said that it is below ^x10 <^-19> A. Since there is Vgs at which the drain current of the transistor is 1 × 10 ⁻²² A or less, the off-state current of the transistor may be 1 × 10 ⁻²² A or less.

  In this specification and the like, the off-state current of a transistor having a channel width W may be represented by a current value flowing around the channel width W. In some cases, the current value flows around a predetermined channel width (for example, 1 μm). In the latter case, the unit of off-current may be represented by a unit having a current / length dimension (for example, A / μm).

  The off-state current of a transistor may depend on temperature. In this specification, off-state current may represent off-state current at room temperature, 60 ° C., 85 ° C., 95 ° C., or 125 ° C. unless otherwise specified. Alternatively, at a temperature at which reliability of the semiconductor device including the transistor is guaranteed or a temperature at which the semiconductor device including the transistor is used (for example, any one temperature of 5 ° C. to 35 ° C.). May represent off-state current. The off-state current of a transistor is I or less means that room temperature, 60 ° C., 85 ° C., 95 ° C., 125 ° C., a temperature at which the reliability of the semiconductor device including the transistor is guaranteed, or the transistor is included. There may be a case where there is a value of Vgs at which the off-state current of the transistor is equal to or lower than I at a temperature (for example, any one of 5 ° C. to 35 ° C.) at which the semiconductor device or the like is used.

  The off-state current of the transistor may depend on the voltage Vds between the drain and the source. In this specification, the off-state current is Vds of 0.1V, 0.8V, 1V, 1.2V, 1.8V, 2.5V, 3V, 3.3V, 10V, 12V, 16V unless otherwise specified. Or an off-current at 20V. Alternatively, Vds in which reliability of a semiconductor device or the like including the transistor is guaranteed, or an off-current in Vds used in the semiconductor device or the like including the transistor may be represented. The off-state current of the transistor is equal to or less than I. Vds is 0.1V, 0.8V, 1V, 1.2V, 1.8V, 2.5V, 3V, 3.3V, 10V, 12V, 16V, 20V There is a value of Vgs at which the off-state current of the transistor in Vds at which the reliability of the semiconductor device including the transistor is guaranteed or Vds used in the semiconductor device including the transistor is equal to or less than I. May be pointed to.

  In the description of the off-state current, the drain may be read as the source. That is, the off-state current sometimes refers to a current that flows through the source when the transistor is off.

  In this specification and the like, the term “leakage current” may be used in the same meaning as off-state current. In this specification and the like, off-state current may refer to current that flows between a source and a drain when a transistor is off, for example.

  The voltage refers to a potential difference between two points, and the potential refers to electrostatic energy (electric potential energy) possessed by a unit charge in an electrostatic field at a certain point. However, generally, a potential difference between a potential at a certain point and a reference potential (for example, ground potential) is simply referred to as a potential or a voltage, and the potential and the voltage are often used as synonyms. Therefore, in this specification, unless otherwise specified, the potential may be read as a voltage, or the voltage may be read as a potential.

  The hybrid display method is a method of displaying a plurality of lights in the same pixel or the same sub-pixel and displaying characters or / and images. The hybrid display is an aggregate that displays a plurality of lights and displays characters or / and images in the same pixel or the same sub-pixel included in the display unit.

  As an example of the hybrid display method, there is a method of displaying the first light and the second light with different display timings in the same pixel or the same sub-pixel. At this time, in the same pixel or the same sub-pixel, the first light and the second light having the same color tone (red, green, or blue, or any one of cyan, magenta, or yellow) are displayed simultaneously. Characters and / or images can be displayed in the section.

  In addition, as an example of the hybrid display method, there is a method of displaying reflected light and self-light emission in the same pixel or the same sub-pixel. Reflected light of the same color and self-emission (for example, OEL light, LED light, etc.) can be simultaneously displayed on the same pixel or the same sub-pixel.

  Note that in the hybrid display method, a plurality of lights may be displayed not in the same pixel or the same sub-pixel but in an adjacent pixel or an adjacent sub-pixel (part of 1). In addition, displaying the first light and the second light at the same time means displaying the first light and the second light for the same period to the extent that the flicker is not sensed by human eyes. If the flicker is not sensed with the sense, the display period of the first light and the display period of the second light may be shifted.

  The hybrid display is an aggregate that includes a plurality of display elements in the same pixel or the same sub-pixel, and each of the plurality of display elements displays in the same period. In addition, the hybrid display includes a plurality of display elements and active elements that drive the display elements in the same pixel or the same sub-pixel. Examples of active elements include switches, transistors, and thin film transistors. Since the active element is connected to each of the plurality of display elements, the display of each of the plurality of display elements can be individually controlled.

(Embodiment 1)
In this embodiment, FIGS. 1 to 8 are used for a display device in which at least one display device provided in a housing of an electronic device has a function of displaying in different directions by a hinge included in the housing. I will explain.

  FIG. 1A illustrates a foldable electronic device. An electronic device 10 illustrated in FIG. 1A includes a housing 11, a housing 12, a hinge 13, and a display device 14. The casing 11 and the casing 12 are coupled to each other by a hinge 13 so as to be rotatable. The electronic device 10 can be deformed into a state in which the housing 11 and the housing 12 are closed, and an open state as shown in FIG. Thereby, when carrying, it is excellent in portability, and when used, it is excellent in visibility due to a large display area.

  Further, it is desirable that the hinge 13 has a lock mechanism so that the angle does not become larger than these angles when the housing 11 and the housing 12 are opened. For example, it is desirable that the angle at which the lock is applied (not opened further) is 90 degrees or more and less than 180 degrees, and typically 90 degrees, 120 degrees, 135 degrees, 150 degrees, 175 degrees, or the like. be able to. Thereby, convenience, safety, and reliability can be improved. In FIG. 1A, an example of locking at 135 degrees will be described.

  The display device 14 functions as a touch panel and can be scanned with a finger or a stylus.

  One of the housing 11 and the housing 12 is provided with a wireless communication module, and data is transmitted via a computer network such as the Internet, a LAN (Local Area Network), and Wi-Fi (Wireless Fidelity: registered trademark). It is possible to send and receive.

  The display device 14 is preferably composed of one flexible display. Thereby, it is possible to perform continuous display without interruption between the housing 11 and the housing 12. In addition, it is good also as a structure by which a display is provided in each of the housing | casing 11 and the housing | casing 12. FIG.

  In the electronic device 10 illustrated in FIG. 1A, a flexible display device 14 is provided across a housing 11 and a housing 12 connected by a hinge 13.

  In FIG. 1A, when the housing 11 and the housing 12 are opened, the display device 14 is held in a greatly curved form. For example, the display device 14 can be held in a state where the radius of curvature is 1 mm to 50 mm, preferably 5 mm to 30 mm. A part of the display device 14 has pixels continuously arranged from the housing 11 to the housing 12 so that curved display can be performed.

  Since the hinge 13 has the lock mechanism described above, the display device 14 can be prevented from being damaged without applying an excessive force to the display device 14. Therefore, a highly reliable electronic device can be realized.

  The display device 14 includes a display area 51, a display area 52, and a display area 53. A display area 51 is arranged in the casing 11, and a display area 52 is arranged in the casing 12. The housing 11 and the housing 12 are connected by a hinge 13, and a display area 53 is disposed in the housing 11, the hinge 13, and the housing 12. Since the display device 430 has a function of fixing the display area 52 at an angle different from that of the display area 51 by the hinge 13, the display area 53 has a curvature, so that a seamless display surface can be configured. .

  The display device 14 has a plurality of pixels 100. FIG. 1B illustrates an example of a cross-sectional structure of the pixel 100 according to one embodiment of the present invention. Although details of the circuit will be described with reference to FIGS. 5A and 5B, the pixel 100 illustrated in FIG. 1B includes a transistor 111, a display element 113, a transistor 121, a transistor 122, and a display element 127. The transistor 111, the display element 113, the transistor 121, the transistor 122, and the display element 127 are located between the substrate 101 and the substrate 102.

  In the pixel 100, the display element 113 includes a pixel electrode 114, a common electrode 115, a reflective electrode 208, and a liquid crystal layer 116. The pixel electrode 114 and the reflective electrode 208 are electrically connected. The pixel electrode 114 is electrically connected to the transistor 111 through the reflective electrode 208. Then, the orientation of the liquid crystal layer 116 is controlled according to the voltage applied between the pixel electrode 114 and the common electrode 115. Note that FIG. 1B illustrates the case where the reflective electrode 208 has a function of reflecting visible light and the common electrode 115 has a function of transmitting visible light, and light incident from the substrate 102 side is illustrated. As shown by the arrow, the light is reflected by the reflective electrode 208 and is emitted again from the substrate 102 side.

  The display element 127 includes a pixel electrode 125, an electroluminescent layer 124, and a common electrode 126. The display element 127 is electrically connected to the transistor 122. Light emitted from the display element 127 is emitted to the substrate 102 side.

  Note that FIG. 1B illustrates a case where the reflective electrode 208 has a function of reflecting visible light and the common electrode 115 has a function of transmitting visible light, and thus light emitted from the display element 127 is illustrated. Passes through the opening region 150H (or the notch region) provided in the reflective electrode 208 as indicated by an arrow as a light guide, passes through the region where the common electrode 115 is located, and is emitted from the substrate 102 side. In this embodiment, the case where the reflective electrode 208 has the opening region 150H is described as an example. However, the reflective electrode 208 may have a notch region.

  In the pixel 100 illustrated in FIG. 1B, the transistor 111, the transistor 121, and the transistor 122 are located in the same layer 200, and the transistor 111, the transistor 122, and the transistor 121 are included. The layer 200 is provided below the display element 113, and the display element 127 is provided above the layer 200. Note that at least when the semiconductor layer included in the transistor 111 and the semiconductor layers included in the transistor 121 and the transistor 122 are located on the surface of the same insulating layer, the transistor 111, the transistor 121, and the transistor 122 are the same. It can be said that it is included in the layer 200.

  With the above structure, the transistor 111, the transistor 121, and the transistor 122 can be manufactured through a common process.

  In the display element 127, it is preferable that a region overlapping the opening region 150H emits light. In order to efficiently use the light emitted from the opening region 150H, the light-emitting region of the display element 127 can be determined by providing the insulating layer 216 with the opening region 160H.

  The display element 127 is formed by providing the pixel electrode 125 in a region overlapping with the opening region 160H, providing the electroluminescent layer 124 under the pixel electrode 125, and providing the common electrode 126 under the electroluminescent layer 124.

  The viewing angle of the display element 127 can be widened by making the display element 127 formed in the opening area 160H larger than the opening area 150H. Therefore, the inside of a straight line connecting the outer peripheral portion of the display element 127 and the outer peripheral portion of the opening region 150H can be used as a light guide path. It is desirable not to arrange a conductive layer in the light guide path. When the conductive layer is disposed in the light guide path, the conductive layer has a high reflectance, so that it becomes a light shielding film, and the light extraction efficiency decreases. Therefore, the gradation changes depending on the viewing angle. However, this is not the case when the conductive layer has translucency.

  FIG. 2 shows a pixel A1 in the display area 51 and a pixel A2 in the display area 52 in FIG. The positional relationship between the display element 113 and the display element 127 included in each of the pixel A1 and the pixel A2 is shown. The pixel A1 shown here is an example when the housing 11 is fixed at a position opened 135 degrees from the closed state. However, in order to simplify the description, it is assumed that the housing 11 is fixed at a position that rises 45 degrees from a position that opens 180 degrees.

  The display element 113 included in the pixel A1 is disposed along the display surface B1 having an angle R45 to which the housing 11 is fixed. The display element 127 is disposed along the display surface B11 located in parallel with the display surface B1. The angle R45 means 45 degrees with respect to the display surface B1. A distance from the position of the reflective electrode included in the display element 113 to the display element 127 can be represented by a distance d. A detailed description of the distance d is shown in FIG.

  The reflective electrode included in the display element 113 has an opening region 150H. The center position of the opening region 150H is disposed so as to overlap with the center position of the opening region 160H in which the display element 127 is disposed. The display element 127 emits light at an angle R90 in the display direction B2 and performs display. The angle R90 means a direction of 90 degrees with respect to the display surface B1. Therefore, when the operator of the electronic device 10 views the display area 51 on the display surface B1 at the position of the angle R90, the gradation and brightness of the display element 127 can be correctly displayed to the operator.

  However, the operator does not always see the display at the optimum angle R90. Therefore, it is necessary to widen the range in which the operator can correctly recognize the gradation of the display element 127. Therefore, it is necessary to widen the viewing angle of the display element 127.

  Therefore, it is desirable that the opening region 160H in which the display element 127 is formed be larger than the opening region 150H. In the pixel A1 of FIG. 2, an example in which the area corresponding to the distance a is set larger than the outer peripheral portion of the opening region 150H is shown. The viewing angle can be controlled by the distance a. The angle formed by the right triangle formed by the distance a and the distance d is the viewing angle. As an example, when the angle R30 is provided with the display direction B2 as the center, the distance a can be obtained from the three-square theorem. In order to realize a viewing angle of 30 degrees, it can be expressed by Equation 1.

  a = d / (√3) (Formula 1)

  Therefore, the viewing angle of the display area 51 included in the housing 11 can be controlled by increasing the area of the display element 127 corresponding to the distance a from the opening area 150H.

  The display element 113 has a function of performing display by reflecting light incident from the incident direction R1 in the direction R2 with a reflective electrode. The reflective electrode has irregularities on the surface and can diffuse and reflect incident light. Therefore, display with a wide viewing angle can be performed regardless of the direction of incident light. Even if the display of the display element 113 is diffused and displayed by the reflective electrode, the display element 127 is not affected.

  Next, the pixel A2 will be described. A display area 52 is disposed in the housing 12, and the display area 52 includes a pixel A2. The pixel A2 shown here is an example when the display is performed with the housing 12 placed horizontally. Alternatively, it may be considered that the electronic device 10 is held and operated by the operator, and the direction of the operator's line of sight is orthogonal to the display area 51.

  The pixel A2 is different from the pixel A1 in that the display element 113 and the housing 12 are arranged along the display surface C1. The display element 127 is arranged along the display surface C11 located in parallel with the display surface C1. Since the pixel A1 and the pixel A2 formed in the display device 14 are formed in the same process, the distance d is the same distance.

  In the pixel A2, an example in which the viewing angle is set to 45 degrees is shown. In order to obtain a viewing angle of 45 degrees, the opening area 160 needs to have an area larger than the opening area 150 by a distance b. The distance b can be managed by Equation 2 from the three-square theorem. The angle R45 means 45 degrees.

  b = d (Formula 2)

  By setting the viewing angle to 45 degrees, the light emission direction of the display element 127 can be aligned with the center of the display direction of the pixel A1. Although the display direction of the pixel A1 and the pixel A2 is different by 45 degrees, the viewing angle is enlarged by controlling the area of the display element 127, and the visibility of the display area 51 and the display area 52 is deteriorated for the operator. It is possible to display without making it.

  The display element 113 of the pixel A2 has a function of performing display by reflecting light incident from the incident direction R3 in the direction R4 with a reflective electrode. The reflective electrode may have unevenness on the surface, and display may be performed by diffusing and reflecting incident light. A wide viewing angle can be displayed regardless of the direction of incident light. Even if the display of the display element 113 is diffused and displayed by the reflective electrode, the display element 127 is not affected.

  FIG. 3 shows the positional relationship when the operator uses the electronic device having the viewing angle shown in FIG. A description will be given using an example in which the display area 51 arranged in the housing 11 and the display area 52 arranged in the housing 12 are fixed at a position opened at 135 degrees (position upright at 45 degrees).

  The display elements 127 included in the pixels of the display area 51 can be displayed in the orthogonal display direction R90B (display direction B2 in FIG. 2). The display element 127 included in the pixel in the display region 52 can be displayed in the display direction R45C by providing the distance b. That is, the viewing angle can be widened.

  Accordingly, since the display direction R90B and the display direction R45C (display direction C2 in FIG. 2) can be displayed in the same direction, the display areas 51 and 52 are arranged at two different angles. Even so, an optimal display can be provided.

  As shown in FIG. 3, if the operator's viewpoint is within the range surrounded by the extension line from R45C to R60B, the electronic device can provide an optimal display. In order to provide an optimal viewing angle corresponding to the angle at which the housing 11 and the housing 12 are fixed, the distance a and the distance b may be set to different distances in order to provide an optimal display. Also, the same distance may be set to provide a wider viewing angle. Furthermore, the distance a and the distance b can not only control the viewing angle with respect to the vertical direction but also widen the viewing angle with respect to the horizontal direction. Therefore, in order to provide a more comfortable display, it is desirable to set the distance a and the distance b in consideration of the hinge fixing angle.

  4A, 4B, and 4C illustrate examples of electronic devices that can be folded differently from those in FIG.

  An electronic device 900 illustrated in FIG. 4A includes a housing 901a, a housing 901b, a hinge 903, a display portion 902, and the like. The display portion 902 is incorporated in the housing 901 and the housing 901b.

  FIG. 4B illustrates an electronic device 910 that functions as a portable game machine. The electronic device 910 includes a housing 911a, a housing 911b, a display portion 912, a hinge 913, an operation button 914a, an operation button 914b, and the like.

  In addition, a cartridge 915 can be inserted into the housing 911b. The cartridge 915 stores application software such as a game, for example. By exchanging the cartridge 915, various applications can be executed by the electronic device 910.

  FIG. 4B illustrates an example in which the size of the portion of the display portion 912 that overlaps with the housing 911a and the size of the portion of the display portion 912 that overlaps with the housing 911b are different. Specifically, a portion of the display portion 912 provided in the housing 911a is larger than a portion of the display portion 912 that overlaps the housing 911b where the operation buttons 914a and 914b are provided. For example, each display unit can be used properly, such as displaying the main screen on the housing 911a side of the display unit 912 and displaying the operation screen on the housing 911b side.

  In the electronic device 920 illustrated in FIG. 4C, a flexible display portion 922 is provided over the housing 921a and the housing 921b which are connected to each other with the hinge 923. The display portion 922 corresponds to the display region 53 having the curvature illustrated in FIG.

  In FIG. 4C, when the housing 921a and the housing 921b are opened, the display portion 922 is held in a significantly curved form. For example, the display portion 922 can be held with a curvature radius of 1 mm to 50 mm, preferably 5 mm to 30 mm. Part of the display portion 922 can display a curved surface by continuously arranging pixels from the housing 921a to the housing 921b.

  Since the hinge 923 has the above-described lock mechanism, the display unit 922 can be prevented from being damaged without applying an excessive force to the display unit 922. Therefore, a highly reliable electronic device can be realized.

  FIG. 5 shows a configuration example of the pixel 100. The pixel 100 includes a pixel circuit 110, and the pixel circuit 110 includes a display element 113. As an example, the display element 113 is preferably AC driven by a voltage in order to prevent burn-in.

  The pixel 100 includes a pixel circuit 120, and the pixel circuit 120 includes a display element 127. The display element 127 is preferably a DC-driven display element as an example.

  The gradation of the display element 113 of the pixel circuit 110 and the display element 127 of the pixel circuit 120 is controlled by a gradation signal corresponding to voltage or current.

  The pixel circuit 110 includes a transistor 111, a capacitor 112, and a display element 113. The display element 113 includes a pixel electrode 114, a liquid crystal layer 116, and a common electrode 115. The pixel electrode 114 is either an anode or a cathode, and the common electrode 115 is either the anode or the cathode.

  A gate of the transistor 111 in the pixel circuit 110 is electrically connected to the scanning line G1. One of a source and a drain of the transistor 111 is electrically connected to the signal line S1.

  The other of the source and the drain of the transistor 111 is electrically connected to one electrode of the capacitor 112 and the pixel electrode 114. The pixel electrode 114 is electrically connected to the common electrode 115 through the liquid crystal layer 116.

  A reference voltage of the capacitive element 112 is applied to the other electrode of the capacitive element 112 via a CSCOM terminal. A common voltage is applied to the common electrode 115 via the VCOM terminal.

  The gray level of the display element 113 is controlled by a voltage generated between the pixel electrode 114 and the common electrode 115 by a gray level signal supplied from the signal line S1.

  The pixel circuit 120 includes a transistor 121, a transistor 122, a capacitor 123, and a display element 127. The display element 127 includes a pixel electrode 125, an electroluminescent layer 124, and a common electrode 126. The pixel electrode 125 is either an anode or a cathode, and the common electrode 126 is either the anode or the cathode.

  A gate of the transistor 121 in the pixel circuit 120 is electrically connected to the scanning line G2. One of a source and a drain of the transistor 121 is electrically connected to the signal line S2.

  The other of the source and the drain of the transistor 121 is electrically connected to one electrode of the capacitor 123 and the gate of the transistor 122. The drain of the transistor 122 is electrically connected to the ANO terminal and the other electrode of the capacitor 123. The pixel electrode 125 is electrically connected to the source of the transistor 122. The pixel electrode 125 is connected to the common electrode 126 through the electroluminescent layer 124.

  An anode voltage is applied to the drain of the transistor 122 via the ANO terminal. A cathode voltage is applied to the common electrode 126 via the VCath terminal.

  Although the example in which the other electrode of the capacitor 123 is electrically connected to the drain of the transistor 122 is described, the electrode may be electrically connected to the source, or may be electrically connected to a wiring or an electrode to which another voltage is applied. You may connect.

  The transistor 122 can control a driving current supplied to the display element 127 by a grayscale signal supplied from the signal line S2. The display element 127 has a function of controlling the gradation of the display element 127 by a driving current flowing through the display element 127.

  FIG. 6 is a bottom view illustrating the pixel 100, and FIG. 6B is a bottom view illustrating a part of the structure illustrated in FIG.

<Configuration example 1>
A pixel 100 described with reference to FIG. 6A includes a pixel circuit 110 and a pixel circuit 120. The pixel includes a signal line S1, a signal line S2, a scanning line G1, a scanning line G2, a pixel circuit 110, a pixel circuit 120, a wiring ANO, and a wiring CSCOM.

  The pixel circuit 110 includes a signal line S1, a scanning line G1, a transistor 111, a capacitor 112, and a reflective electrode 208 having a function of a pixel electrode. The pixel circuit 120 includes a signal line S2, a scanning line G2, a transistor 121, a transistor 122, a capacitor 123, and a pixel electrode 125. A bottom view in which the pixel electrode 125 is omitted is shown in FIG. 6B, and the display element 127 is shown at the position of the opening region 150H. The display element 127 is located at the same position as the opening region 160H. Hereinafter, description will be made with reference to FIG.

  In the pixel circuit 110, one of the source and the drain of the transistor 111 is electrically connected to the signal line S1, and the other of the source and the drain of the transistor 111 is electrically connected to the pixel electrode 114 through the contact 131. Yes. Further, the other of the source and the drain of the transistor 111 is electrically connected to one electrode of the capacitor 112. In addition, a wiring CSCOM is electrically connected to the other electrode of the capacitor 112. A display element 113 is formed below the pixel electrode 114 as shown in FIG.

  In the pixel circuit 120, one of the source and the drain of the transistor 121 is electrically connected to the signal line S 2, and the other of the source and the drain of the transistor 121 is electrically connected to the gate of the transistor 122 through the contact 134. ing. The drain of the transistor 122 is electrically connected to the wiring ANO through the contact 130. The drain of the transistor 122 is electrically connected to the pixel electrode 125 through the contact 132. The capacitor 123 is formed using a region where the wiring ANO and the wiring connected to the gate of the transistor 122 overlap. A display element 127 is formed over the pixel electrode 125 as illustrated in FIG.

  A specific example of the structure of the pixel circuit 110 using a reflective display element and the pixel circuit 120 using a display element will be described using the pixel 100 illustrated in FIG. 6B as an example.

  FIG. 7 shows an example of a cross-sectional structure of the pixel 100. 7 is a cross-sectional structure taken along cutting lines X1-X2 and X3-X4 in FIG.

  FIG. 7A illustrates a cross-sectional configuration example of the pixel circuit 110, and FIG. 7B illustrates a cross-sectional configuration example of the pixel circuit 120. FIG. 7A has a structure in which a pixel circuit 103 is provided between the substrate 101 and the substrate 102.

  FIG. 7A is a cross-sectional view of the pixel circuit 110 in FIG. 6B taken along the cutting line X1-X2. The cutting line X1-X2 cuts the opening region 150H for emitting light of the display element 127 included in the pixel circuit 120, the capacitor element 112, the contact 131, and the transistor 111. Further, the display element 127 of the pixel circuit 120 is disposed in a region overlapping with the opening region 150H.

  The transistor 111 includes an insulating layer 210, a conductive layer 201a below the insulating layer 210, an insulating layer 211 located under the conductive layer 201a and functioning as a gate, and a conductive layer 201a below the insulating layer 211. An overlapping oxide semiconductor layer 202a, an insulating layer 212 having a function of a passivation layer under the oxide semiconductor layer 202a, a conductive layer 203a electrically connected to the oxide semiconductor layer 202a, and a conductive layer 203b.

  The insulating layer 213 below the insulating layer 212 is also provided below the oxide semiconductor layer 202a. The insulating layer 213 which overlaps under the oxide semiconductor layer 202a also functions as a moisture-proof layer.

  If the transistor 111 deteriorates due to intrusion of impurities such as moisture from the outside, the gradation of the pixel cannot be controlled correctly. Therefore, the display deteriorates. The moisture-proof film has a function of suppressing the entry of water from the outside. Therefore, the insulating layer 213 is preferably formed using a silicon nitride film, a nitrogen oxide silicon film, or the like.

  Here, a reflective liquid crystal element formed over the transistor 111 is described. Since the transistor 111 is electrically connected to the pixel electrode 114 through the contact 131, the insulating layer 210 has an opening region. In the contact 131, the conductive layer 203a and the reflective electrode 208 are electrically connected through the conductive layer 201b. The reflective electrode 208 includes a conductive layer 208a, a conductive layer 208b, and a conductive layer 208c. The reflective electrode 208 is electrically connected to the pixel electrode 114.

  The display element 113 includes a pixel electrode 114, a liquid crystal layer 116, and a common electrode 115. The pixel electrode 114 includes an alignment film AF1 that controls the alignment of the liquid crystal, the liquid crystal layer 116 on the alignment film AF1, the alignment film AF2 on the liquid crystal layer 116, and the common electrode 115 on the alignment film AF2. . Further, an insulating layer 218 is provided on the common electrode 115, and a coloring layer CF1 is provided in the display region of the pixel 100. Further, a light shielding film BM may be provided to separate pixels.

  Note that one embodiment of the present invention is not limited to the color filter method, and a color separation method, a color conversion method, a quantum dot method, or the like may be applied. Further, the alignment film may not be used.

  The pixel electrode 114 and the common electrode 115 are light-transmitting conductive layers. When the display element 113 is used as a reflective liquid crystal element, the pixel electrode has a function of reflecting incident light. Therefore, the pixel electrode 114 includes the reflective electrode 208 between the conductive layer 201b.

  The pixel 100 includes a pixel circuit 120. As will be described in detail with reference to FIG. 7B, the display element 127 included in the pixel circuit 120 has a function of emitting light in the direction of the substrate 102. Therefore, the pixel electrode 114 and the common electrode 115 have a function of transmitting light. The reflective electrode 208 desirably has an opening region 150H that functions as a light guide path for light emitted from the display element 127, and further has a function of reflecting external light received from outside the substrate 102.

  It is desirable that the reflective electrode 208 has an effect of increasing the reflectance. By increasing the reflectivity, high brightness can be obtained when performing reflective display with external light. The surface of the conductive layer 208a may have unevenness. By having the unevenness, a function of irregularly reflecting external light received from the outside of the substrate 102 can be provided. By irregularly reflecting light with the conductive layer 208a, light can be reflected in various directions without depending on the incident direction of external light. Therefore, the viewing angle can be widened. Further, the reflective electrode 208 has a light shielding function for protecting the transistor from external light.

  As the conductive material having a visible light-transmitting property, for example, a material containing one kind selected from indium (In), zinc (Zn), and tin (Sn) may be used. Specifically, indium oxide, indium tin oxide (Indium Tin Oxide), indium zinc oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, titanium oxide Indium tin oxide containing silicon, indium tin oxide containing silicon oxide, zinc oxide, zinc oxide containing gallium, and the like can be given. Note that a film containing graphene can also be used. The film containing graphene can be formed, for example, by reducing a film containing graphene oxide formed in a film shape.

  Examples of the conductive material that reflects visible light include aluminum, silver, and alloys containing these metal materials. In addition, a metal material such as gold, platinum, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium, or an alloy containing these metal materials can be used. In addition, lanthanum, neodymium, germanium, or the like may be added to the metal material or alloy. Alloys containing aluminum such as aluminum and titanium alloys, aluminum and nickel alloys, aluminum and neodymium alloys, aluminum, nickel, and lanthanum alloys (Al-Ni-La), silver and copper alloys, An alloy containing silver such as an alloy of silver, palladium, and copper (also referred to as Ag-Pd-Cu, APC), an alloy of silver and magnesium, or the like may be used.

  The reflective electrode 208 may be composed of a plurality of conductive layers. As an example, the conductive layer 208a that functions as a reflective layer, the conductive layer 208b that has a function of reflecting the wavelength in the ultraviolet region included in external light, and the conductive layer 208c can electrically connect the conductive layer 201b and the conductive layer 208c with low resistance. Can be configured to be connected to each other.

  For example, it is known that aluminum has a high reflectance with respect to visible light and also has a high reflectance with respect to wavelengths in the ultraviolet region of 290 nm to 390 nm. Therefore, by using aluminum for the conductive layer 208b, the reflective electrode has a function of protecting the transistor from ultraviolet rays under external light. In this embodiment mode, an example of three layers is shown; however, it may be formed of one conductive layer, two layers, or a plurality of layers.

  The pixel circuit 110 includes a capacitor 112 that holds a gradation signal for display by a reflective liquid crystal element. The capacitor 112 is formed by the insulating layer 211 located between the conductive layer 203a and the conductive layer 201e.

  The opening region 150 </ b> H included in the reflective electrode 208 functions as a light guide that emits light emitted from the display element 127 controlled by the pixel circuit 120 and emits the light toward the substrate 102. The display element 127 can perform display with a gradation different from that of the display element 113 controlled by the pixel circuit 110.

  Although details will be described with reference to FIG. 7B, the opening region 160H in which the display element 127 is formed is preferably larger than the opening region 150H. As an example, in FIG. 7A, the opening region 160H in which the display element 127 is arranged corresponds to an area widened by a distance a from the outer peripheral portion of the opening region 150H.

  As shown in FIG. 7A, the distance from the conductive layer 208a constituting the reflective electrode 208 to the display element 127 is a distance d, and the difference between the outer periphery of the opening region 150H and the outer periphery of the opening region 160H is a distance a. A right triangle designated by vertex X, vertex Y, and vertex Z can be considered. An angle formed by a straight line connecting the vertex X to the vertex Z and a straight line connecting the vertex Y to the vertex Z corresponds to the viewing angle of the display element 127. When the viewing angle is set to 30 degrees, the distance a can be calculated by Expression 1, and when the viewing angle is set to 45 degrees, it can be calculated by Expression 2.

  FIG. 7B illustrates a cross-sectional configuration example of the pixel circuit 120. FIG. 7B has a structure in which the pixel circuit 103 is provided between the substrate 101 and the substrate 102.

  FIG. 7B is a cross-sectional view of the pixel circuit 120 in FIG. 6B taken along the cutting line X3-X4. The cutting line X3-X4 cuts the contact 132, the transistor 122, the contact 130, and the opening region 150H. Further, the display element 127 of the pixel circuit 120 is disposed in a region overlapping with the opening region 150H.

  The transistor 122 includes the insulating layer 210, the conductive layer 201c under the insulating layer 210, the insulating layer 211 located under the conductive layer 201c and functioning as a gate, and the conductive layer 201c under the insulating layer 211. An oxide semiconductor layer 202b that overlaps with the oxide semiconductor layer 202b, an insulating layer 212 that functions as a passivation layer under the oxide semiconductor layer 202b, a conductive layer 203d that is electrically connected to the oxide semiconductor layer 202b, A layer 203e.

  The conductive layer 203d is electrically connected to the oxide semiconductor layer 202b, and the conductive layer 203e is electrically connected to the oxide semiconductor layer 202b. The conductive layer 203e is electrically connected to the conductive layer 201d through the contact 130. The conductive layer 203d is electrically connected to the pixel electrode 125 through the contact 132. The conductive layer 201c and the conductive layer 201d are formed of the same layer.

  The insulating layer 213 below the oxide semiconductor layer 202b functions as a moisture-proof layer.

  The display element 127 includes a pixel electrode 125, an electroluminescent layer 124, and a common electrode 126. The electroluminescent layer 124 is provided under the pixel electrode 125 and the common electrode 126 is provided under the electroluminescent layer 124 at a position overlapping the opening region 150H. The pixel electrode 125 is electrically connected to the common electrode 126.

  By supplying current from the transistor 122 to the electroluminescent layer 124 through the contact 132, the gray level of the display element 127 is controlled. The display element 127 has a function of emitting light in the direction of the substrate 102 using the opening region 150H as a light guide path.

  The display element 127 preferably emits light in a larger area than the region overlapping the opening region 150H. By increasing the opening area 160H, the light extraction angle is widened, and the change in gradation due to the viewing angle can be suppressed. However, in order to efficiently use the light radiated from the opening region 150H, it is preferable that the display element 127 disposed under the reflective electrode 208 that does not affect the expansion of the viewing angle does not emit light. Therefore, the light-emitting region of the display element 127 can be determined by providing the insulating layer 216 with the opening region 160H.

  An insulating layer 215 is provided as a planarization film under the insulating layer 213. A contact 132 is provided on the insulating layer 215, and a pixel electrode 125 is provided below the contact 132. An insulating layer 216 is provided under the pixel electrode 125, and an opening region 160H is provided. An electroluminescent layer 124 is provided in a region overlapping with the opening region 160 </ b> H, and a common electrode 126 is provided under the electroluminescent layer 124.

  The insulating layer 215 is preferably an organic insulating film. As the organic insulating film, a film made of polyimide, polyamide, BCB (benzocyclobutene), acrylic, positive photosensitive organic resin, negative photosensitive organic resin, or the like can be used.

  FIG. 7B shows a part of the display element 127 arranged in the opening region 160H having an area wider than the opening region 150H corresponding to the distance a from the outer periphery of the opening region 150H. Similarly to FIG. 7A, the distance a can be determined according to the viewing angle to be set.

  FIG. 7B illustrates an example in which the coloring layer CF1 is disposed at a position overlapping the opening region 150H and further covering the viewing angle of the display element 127. However, the colored layer CF1 is not necessarily required. In the case where color display is performed using a white display element as the display element 127, a structure having a colored layer CF1 is desirable. However, when a monochromatic display element that emits light of R, G, and B is used, a structure that does not use the colored layer CF1 is desirable. Alternatively, even when a monochrome display element that emits light of R, G, and B is used, higher color purity can be obtained by using the colored layer CF1.

  Note that the conductive layer 204a may be provided over the oxide semiconductor layer 202a included in the transistor or the insulating layer 212 located under the oxide semiconductor layer 202b. The conductive layer 204a functions as a back gate electrode. A region larger than a region where the oxide semiconductor layer 202a and the insulating layer 212 are in contact with each other and a sidewall of the oxide semiconductor layer 202a or the oxide semiconductor layer 202b is preferably covered.

  8A is formed with the conductive layer 204a when the back gate is provided over the channel formation region of the transistor 111, the transistor 121, or the transistor 122 in FIGS. 7A and 7B. can do. Further, FIG. 8B illustrates a top-gate transistor. By using the top gate structure, the capacitive load of the scanning line can be reduced.

  In a transistor having a back gate, the back gate is preferably electrically connected to the gate or source of the transistor. Since the transistor has a back gate, the reliability of the transistor can be improved. Further, since the on-state current can be increased, the size of the transistor can be reduced. However, the back gate may be electrically connected to another wiring. The connection destination can be selected according to the characteristics of the circuit.

  There is no particular limitation on the crystallinity of a semiconductor material used for the transistor, and there is no limitation on an amorphous semiconductor or a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor partially including a crystal region). Any of them may be used.

  As a semiconductor material used for the transistor, an oxide semiconductor can be used. Typically, an oxide semiconductor containing indium can be used.

  In particular, it is preferable to use a semiconductor material having a wider band gap and lower carrier density than silicon because current in the off-state of the transistor can be reduced.

  Note that here, an In—Ga—Zn-based oxide means an oxide containing In, Ga, and Zn as its main components, and there is no limitation on the ratio of In, Ga, and Zn. Moreover, metal elements other than In, Ga, and Zn may be contained. A transistor including an oxide semiconductor in a semiconductor layer will be described in detail in Embodiment 4.

  Note that in this embodiment mode, the structure of a display device using a liquid crystal element as a reflective display element is illustrated, but as a reflective display element, in addition to a liquid crystal element, a shutter-type MEMS (Micro Electro Mechanical System) element is used. An optical interference type MEMS device, a microcapsule method, an electrophoresis method, an electrowetting method, an electronic powder fluid (registered trademark) method, or the like can be used.

  In addition, as the light-emitting display element, for example, a self-luminous display element such as an OLED (Organic Light Emitting Diode), an LED (Light Emitting Diode), or a QLED (Quantum-dot Light Emitting Diode) can be used.

  As the liquid crystal element, for example, a liquid crystal element to which a vertical alignment (VA: Vertical Alignment) mode is applied can be used. As the vertical alignment mode, an MVA (Multi-Domain Vertical Alignment) mode, a PVA (Patterned Vertical Alignment) mode, an ASV (Advanced Super View) mode, or the like can be used.

  As the liquid crystal element, liquid crystal elements to which various modes are applied can be used. For example, in addition to the VA mode, a TN (Twisted Nematic) mode, an IPS (In-Plane-Switching) mode, an FFS (Fringe Field Switching) mode, an ASM (Axially Symmetrical Aligned Micro-cell) mode Further, a liquid crystal element to which an FLC (Ferroelectric Liquid Crystal) mode, an AFLC (Antiferroelectric Liquid Crystal) mode, or the like is applied can be used.

  As the liquid crystal used in the liquid crystal element, a thermotropic liquid crystal, a low molecular liquid crystal, a polymer liquid crystal, a polymer dispersed liquid crystal (PDLC), a ferroelectric liquid crystal, an antiferroelectric liquid crystal, or the like is used. Can do. These liquid crystal materials exhibit a cholesteric phase, a smectic phase, a cubic phase, a chiral nematic phase, an isotropic phase, and the like depending on conditions.

  Further, as the liquid crystal material, either a positive type liquid crystal or a negative type liquid crystal may be used, and an optimal liquid crystal material may be used according to an applied mode or design.

  An alignment film can be provided to control the alignment of the liquid crystal. Note that in the case of employing a horizontal electric field mode, liquid crystal exhibiting a blue phase for which an alignment film is unnecessary may be used. The blue phase is one of the liquid crystal phases. When the temperature of the cholesteric liquid crystal is increased, the blue phase appears immediately before the transition from the cholesteric phase to the isotropic phase. Since the blue phase appears only in a narrow temperature range, a liquid crystal composition mixed with several percent by weight or more of a chiral agent is used for the liquid crystal layer in order to improve the temperature range. A liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent has a short response speed and is optically isotropic. In addition, a liquid crystal composition including a liquid crystal exhibiting a blue phase and a chiral agent does not require alignment treatment and has a small viewing angle dependency. Further, since it is not necessary to provide an alignment film, a rubbing process is not required, so that electrostatic breakdown caused by the rubbing process can be prevented, and defects or breakage of the liquid crystal display device during the manufacturing process can be reduced. .

  Note that one embodiment of the present invention is described in this embodiment. Alternatively, in another embodiment, one embodiment of the present invention is described. Note that one embodiment of the present invention is not limited thereto. That is, in this embodiment and other embodiments, various aspects of the invention are described, and thus one embodiment of the present invention is not limited to a particular aspect. For example, although an example in which the present invention is applied to a display device is shown as one embodiment of the present invention, one embodiment of the present invention is not limited thereto. In some cases or depending on circumstances, one embodiment of the present invention may not be applied to a display device. For example, one embodiment of the present invention may be applied to a semiconductor device having another function. For example, although an example in which a channel formation region, a source / drain region, and the like of a transistor include an oxide semiconductor is described as one embodiment of the present invention, one embodiment of the present invention is not limited thereto. Depending on circumstances or conditions, various transistors in one embodiment of the present invention, a channel formation region of the transistor, a source / drain region of the transistor, or the like may include various semiconductors. Depending on circumstances or conditions, various transistors in one embodiment of the present invention, a channel formation region of the transistor, a source / drain region of the transistor, or the like can be formed using, for example, silicon, germanium, silicon germanium, silicon carbide, or gallium. At least one of arsenic, aluminum gallium arsenide, indium phosphide, gallium nitride, or an organic semiconductor may be included. Alternatively, for example, depending on circumstances or circumstances, a variety of transistors, channel formation regions of the transistors, source and drain regions of the transistors, and the like of the transistor may not include an oxide semiconductor. Good.

  The structures and methods described in this embodiment can be combined as appropriate with any of the structures and methods described in the other embodiments.

(Embodiment 2)
[Configuration example of display device]
FIG. 9A is a schematic perspective view of a display device 300 of one embodiment of the present invention. The display device 300 has a structure in which a substrate 351 and a substrate 361 are attached to each other. In FIG. 9A, the substrate 361 is clearly indicated by a broken line.

  Further, a touch sensor can be provided over the substrate 361. For example, a structure may be employed in which a sheet-like capacitive touch sensor 368 is provided over the display portion 362. Alternatively, a touch sensor may be provided between the substrate 361 and the substrate 351. In the case where a touch sensor is provided between the substrate 361 and the substrate 351, an optical touch sensor using a photoelectric conversion element may be used in addition to the capacitive touch sensor.

  The display device 300 corresponds to the display device 14 described in Embodiment 1, and the display unit 362 corresponds to the display areas 51 to 53.

  FIG. 9B illustrates an example in which a touch sensor is provided in the display module 8000 used in the display device 300. The display module 8000 includes a display panel 8006, a frame 8009, a printed board 8010, and a battery 8011 connected to the FPC 8005 between an upper cover 8001 and a lower cover 8002. As the display panel 8006, the display device 300 in FIG. 16A can be used.

  For example, a display device manufactured using one embodiment of the present invention can be used for the display panel 8006. Thereby, a display module can be manufactured with a high yield.

  The shapes and dimensions of the upper cover 8001 and the lower cover 8002 can be changed as appropriate in accordance with the size of the display panel 8006.

  Further, a touch panel may be provided over the display panel 8006. As the touch panel, a resistive film type or capacitive type touch panel can be used by being superimposed on the display panel 8006. Further, without providing a touch panel, the display panel 8006 can have a touch panel function.

  The frame 8009 has a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed board 8010 in addition to a protective function of the display panel 8006. The frame 8009 may have a function as a heat sink.

  The printed board 8010 includes a power supply circuit, a signal processing circuit for outputting a video signal and a clock signal. As a power supply for supplying power to the power supply circuit, an external commercial power supply may be used, or a power supply using a battery 8011 provided separately may be used. The battery 8011 can be omitted when a commercial power source is used.

  The display module 8000 may be additionally provided with a member such as a polarizing plate, a retardation plate, or a prism sheet.

  FIG. 9B is a schematic cross-sectional view of a display module 8000 including an optical touch sensor.

  The display module 8000 includes a light emitting unit 8015 and a light receiving unit 8016 provided on the printed board 8010. Further, a region surrounded by the upper cover 8001 and the lower cover 8002 has a pair of light guide portions (light guide portion 8017a and light guide portion 8017b).

  The display panel 8006 is provided so as to overlap the printed board 8010 and the battery 8011 with a frame 8009 interposed therebetween. The display panel 8006 and the frame 8009 are fixed to the light guide unit 8017a and the light guide unit 8017b.

  Light 8018 emitted from the light emitting unit 8015 passes through the upper part of the display panel 8006 by the light guide unit 8017a and reaches the light receiving unit 8016 through the light guide unit 8017b. For example, the light 8018 is blocked by a detection object such as a finger or a stylus, whereby a touch operation can be detected.

  For example, a plurality of light emitting units 8015 are provided along two adjacent sides of the display panel 8006. A plurality of light receiving portions 8016 are provided at positions facing the light emitting portion 8015 with the display panel 8006 interposed therebetween. Thereby, the information on the position where the touch operation is performed can be acquired.

  The light emitting unit 8015 can use a light source such as an LED element. In particular, as the light emitting unit 8015, it is preferable to use a light source that emits infrared rays that are not visually recognized by the user and are harmless to the user.

  The light receiving unit 8016 can be a photoelectric element that receives light emitted from the light emitting unit 8015 and converts the light into an electrical signal. Preferably, a photodiode capable of receiving infrared light can be used.

  As the light guide portion 8017a and the light guide portion 8017b, a member that transmits at least light 8018 can be used. By using the light guide unit 8017a and the light guide unit 8017b, the light emitting unit 8015 and the light receiving unit 8016 can be arranged below the display panel 8006, and external light reaches the light receiving unit 8016 and the touch sensor malfunctions. Can be suppressed. In particular, it is preferable to use a resin that absorbs visible light and transmits infrared rays. Thereby, malfunction of a touch sensor can be controlled more effectively.

  Here, the description returns to the display device 300. The display device 300 includes a display portion 362, a circuit portion 364, a wiring 365, a circuit portion 366, and the like. The substrate 351 is provided with, for example, a circuit portion 364, a wiring 365, a circuit portion 366, an electrode 311b that functions as a pixel electrode, and the like. FIG. 16 shows an example in which an IC 373 and an FPC 372 are mounted on a substrate 351. Therefore, the structure illustrated in FIG. 16 can also be referred to as a display module including the display device 300, the IC 373, and the FPC 372.

  As the circuit portion 364 and the circuit portion 366, for example, a circuit that functions as a scan line driver circuit can be used.

  The wiring 365 and the wiring 367 have a function of supplying signals and power to the display portion and the circuit portion 364. The signal and power are input to the wiring 365 from the outside or the IC 373 via the FPC 372.

  FIG. 9 illustrates an example in which the IC 373 is provided on the substrate 351 by a COG (Chip On Glass) method or the like. As the IC 373, for example, an IC having a function as a scan line driver circuit can be used. Note that in the case where the display device 300 includes a circuit that functions as a scan line driver circuit and a signal line driver circuit, or a circuit that functions as a scan line driver circuit or a signal line driver circuit is provided outside, and the display device 300 is driven through the FPC 372. For example, the IC 373 may not be provided in the case of inputting a signal to do so. The IC 373 may be provided on the substrate 351 by a COF (Chip On Film) method or the like.

  FIG. 9 shows an enlarged view of a part of the display unit 362. The display portion 362 corresponds to the display areas 51 to 53 described in the first embodiment. In the display portion 362, electrodes 311b included in the plurality of display elements are arranged in a matrix. The electrode 311b has a function of reflecting visible light, and the electrode 311b corresponds to the reflective electrode 280 of the display element 113 in Embodiment 1.

  As shown in FIG. 9, the electrode 311b has an opening. Further, the display element 360 is provided on the substrate 351 side of the electrode 311b. Light from the display element 360 is emitted to the substrate 361 side through the opening of the electrode 311b. The display element 360 corresponds to the display element 127 of the first embodiment.

(Embodiment 3)
In this embodiment, an example in which the display device of Embodiment 1 is applied to a navigation system as an application example will be described with reference to FIGS.

  A navigation system 930 shown in FIG. 10A has a foldable structure. FIG. 10A illustrates a configuration example of the navigation system 930. FIG. 10B is a system block diagram of the navigation system 930.

  A navigation system 930 illustrated in FIG. 10A includes a housing 11, a housing 12, a hinge 13, a display device 14, a camera 413a, a camera 413b, an optical sensor 417, a speaker 419, a microphone 420, and the like. The display device 430 is incorporated in the housing 11 and the housing 12. A touch sensor 418 is disposed at a position overlapping the display device 14.

  The casing 11 and the casing 12 are coupled to each other by a hinge 13 so as to be rotatable. The navigation system 930 can be deformed into a state in which the housing 11 and the housing 12 are closed, and an open state as shown in FIG. Thereby, when carrying, it is excellent in portability, and when used, it is excellent in visibility due to a large display area. Further, it is desirable that the hinge 13 has a lock mechanism so that the angle does not become larger than these angles when the housing 11 and the housing 12 are opened. FIG. 10A shows an example in which the lock is applied at 135 degrees.

  The display device 430 includes a display area 51, a display area 52, and a display area 53, and includes the pixels illustrated in FIG. A display area 51 is arranged in the casing 11, and a display area 52 is arranged in the casing 12. The housing 11 and the housing 12 are connected by a hinge 13, and a display area 53 is disposed in the housing 11, the hinge 13, and the housing 12. Since the display device 430 has a function of fixing the display area 52 at an angle different from that of the display area 51 by the hinge 13, the display area 53 has a curvature, so that a seamless display surface can be configured. .

  FIG. 10B is a system block diagram of the navigation system 930. The navigation system 930 includes a CPU 410, a display controller 411, a memory 412, a camera 413 (camera 413a and camera 413b), a GPS communication module 414, a gyro sensor 415, an acceleration sensor 416, an optical sensor 417, a touch sensor 418, a speaker 419, and a microphone 420. , A battery 421, a communication module 422, a display device 430, and the like. Note that the camera 413 a is provided in the rear surface region of the housing 11.

  The CPU 400 has a function of managing the entire system by a control program stored in the memory 412. The control program can communicate with peripheral devices as necessary. The navigation system 930 has a function of integrating the position information acquired from the GPS communication module and the map information and displaying them on the display device 430.

  The display device 430 includes a reflective liquid crystal display device 431 that displays using a reflective liquid crystal element that displays using reflection of external light, and a light emitting display device 432 that uses a self-light emitting element, using an optical sensor 417. Ambient light can be detected and an optimal display method can be selected and displayed.

  In a bright environment such as under sunlight, display is performed using the reflective liquid crystal display device 431. In an environment where external light cannot be obtained, display is performed using the light emitting display device 432, and under a fluorescent lamp, In an environment where sufficient external light cannot be obtained, such as in a tunnel, hybrid display can be performed using both the reflective liquid crystal display device 431 and the light emitting display device 432.

  The display device 430 preferably has a function of individually updating the display area 51, the display area 52, and the display area 53. Therefore, the gate driver that controls the display of the display device 430 is preferably a decoder type. A decoder type gate driver can select a scanning line to which a pixel whose display is to be updated is connected, and thus is suitable for managing the display update. The display update may be managed by a gate driver using a shift register.

  The memory 412 has a function of a frame memory of the display controller 411. The display controller 411 is used as a primary holding area for data for switching between the reflective liquid crystal display device 431 and the light emitting display device 432 according to the use situation and sending a signal to the display device 430.

  The camera 413a (provided on the housing 11 and not displayed in FIG. 10A) has a function of acquiring a captured image corresponding to incident light. An image obtained by adding information such as a destination direction, a travel distance, and a route to the image captured by the camera 413a can be displayed.

  The gyro sensor 415 has a function of outputting a change in direction as an electrical signal. By recognizing the orientation of the terminal, navigation accuracy can be improved.

  The acceleration sensor 416 has a function of outputting tilt and acceleration information as an electrical signal. The output information of the acceleration sensor 416 can be used to recognize the terminal position when GPS information cannot be acquired.

  Control such as setting, activation, and termination of the navigation system 930 is performed by a signal input from the touch sensor 418. Further, setting, activation, termination, and the like are controlled using the camera 413b, the speaker 419, the microphone 420, the communication module 422, and the like for making a call, a videophone call, a chat, an email, and the like.

  FIG. 11 shows a display mode of the navigation system 930 as an example. There are three display modes, and the display of the display areas 51 to 53 can be switched according to each display mode.

  Mode 1 can display a menu and set the navigation system 930. Various settings can be made such as destination, relay point, selection of information during navigation, and setting of information type. For the operator, the convenience can be enhanced by setting the route while looking at the map. Map information may be displayed in the display area 51, and setting information may be displayed in the display areas 52 and 53. The operator can freely change the display contents.

  In display of still images such as setting information, a transistor including an oxide semiconductor in a semiconductor layer has less off-leakage, and thus display update can be reduced. Therefore, power consumption can be reduced when displaying still images. A transistor including an oxide semiconductor in a semiconductor layer will be described in detail in Embodiment 4. By combining with a decoder type gate driver, the display area can be selected, the frame update rate can be managed, and the power consumption can be further reduced.

  Mode 2 displays position information and map information during navigation. Navigation information is displayed in the display area 51, and navigation route information, branch point distance information, and the like are displayed in the display area 52. In the display area 53, distance information to the next branch point, for example, a place name of an intersection can be displayed.

  The display example shown in FIG. 10A shows Mode 2 as an example. Mode 2 is calculated from the position information detected by the GPS module by registering the distance to the branch point on the setting screen, and can be automatically switched to display of Mode 2. However, it can always be fixed to the display method of Mode2 or Mode3.

  Mode 3 displays position information and map information during navigation. The display areas 51 to 53 can be used as one display area. When there is notification information during navigation, it has a function of displaying in the display area 53 having curvature.

  Since the notification information is interrupted and displayed in the display area 53, it is preferably highlighted. Emphasis display has an effect of improving visibility and cognition. As the types of notification information, communication tools such as telephone calls, videophone calls, chats, and emails, nearby store information, event information, and the like can be displayed. The type of notification information can be set in Mode1.

  Mode 2 and Mode 3 can be automatically switched by setting. Also, the notification information can be displayed only in the display area 53 in the Mode 2 display mode.

  The navigation system 930 shown in this embodiment mode is small and excellent in portability. Therefore, it can be carried during exercises such as walking, jogging and marathon. Furthermore, it can also be installed in a moving means that moves with wheels or a motor as power. The moving means can be installed on a bicycle, a bicycle with an electric motor, a motorcycle, a car, a train, an airplane, a ship, and the like. Since the display angle can be changed by having the hinge 13, the installation area can be reduced. Therefore, it can be installed easily and can be easily attached and detached.

  In addition, the display area is wide and a large amount of information can be displayed. By matching the viewing angles of the display area 51 and the display area 52, the visibility does not deteriorate even in a foldable configuration. In addition, since the display area 53 has a curved surface, the display areas 51 to 53 can be used as one display area to provide a seamless display when viewing map information and the like.

  In addition, during navigation, there are various types of external light, such as environments where there is no outside light such as early morning or night, fluorescent or special light sources such as in tunnels or buildings, and extremely bright environments such as under sunlight. There are changes. In any case, the CPU can determine from position information from the optical sensor 417 and the GPS communication module 414, and provides an optimal display by combining the reflective liquid crystal display device 431 and the light emitting display device 432. be able to.

  FIG. 12 shows the processing of the navigation system 930 in a flowchart.

  Step1 performs setting in Mode1.

  Step 2 sets the destination in Mode 1. If the destination is not set for navigation, the process returns to Step 1.

  In Step 3, route guidance using the navigation system starts. The display mode of Mode 3 is set, and the map information and information on the current position detected by the GPS communication module 414 are displayed in the display areas 51 to 53.

  Step 4 newly acquires current position information from the GPS communication module 414. Based on the display mode of Mode3.

  Step 5 determines whether it is necessary to display near the branch point. If it is not necessary to display, the process proceeds to STEP7.

  Step 6 indicates that it is within the distance for displaying the branch point in Step 5. The display mode shifts to Mode 2, and display objects such as a guidance display 61 and a direction instruction 62 are displayed in the display area 51 as shown in FIG. The display area 52 displays details of the branch points assumed earlier from the current position as a list. The display area 53 displays details regarding the latest branch. The display area 53 can prompt the operator to call attention using various methods such as brightness, painting, and blinking. In the display area 53, the display method can be selected by setting Step1. After passing through the branch point, the process proceeds to Step 7.

  In Step 7, the display mode is determined in Mode 2 or Mode 3. If there is notification information to the operator, the information in the display area 53 is updated. If there is no notification information, the process proceeds to Step 9.

  Step 8 displays the notification information in the display area 53. As types of notification information, notifications from communication tools such as telephone calls, videophone calls, chats, and emails, or nearby store information and event information can be displayed. After the display is completed, the process proceeds to Step 9.

  Step 9 updates the map information and the current position information based on the information from the GPS communication module 414 in Step 4.

  Step 10 determines whether the destination has been reached. When arriving at the destination, display one of the display areas 51 to 53, or all of the display areas 51 to 53 as one display area, and display details such as destination arrival display, travel distance, and travel time. Navigation can be terminated. If the destination is not reached and navigation is in progress, the process proceeds to Step 4.

  By executing these Steps, comfortable display and route guidance can be realized using the foldable navigation system 930.

  The structures and methods described in this embodiment can be combined as appropriate with any of the structures and methods described in the other embodiments.

(Embodiment 4)

[Transistor]
The transistor includes a conductive layer that functions as a gate electrode, a semiconductor layer, a conductive layer that functions as a source electrode, a conductive layer that functions as a drain electrode, and an insulating layer that functions as a gate insulating layer. FIG. 7 shows the case where a bottom-gate transistor is applied.

  Note that there is no particular limitation on the structure of the transistor included in the display device of one embodiment of the present invention. For example, a planar transistor, a staggered transistor, or an inverted staggered transistor may be used. Further, a top-gate or bottom-gate transistor structure may be employed. Alternatively, gate electrodes may be provided above and below the channel.

  There is no particular limitation on the crystallinity of a semiconductor material used for the transistor, and any of an amorphous semiconductor and a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor partially including a crystal region) is used. May be used. It is preferable to use a crystalline semiconductor because deterioration of transistor characteristics can be suppressed.

  As a semiconductor material used for the transistor, a metal oxide having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more can be used. Typically, a metal oxide containing indium, for example, a CAC-OS described later can be used.

  A transistor using a metal oxide having a wider band gap and lower carrier density than silicon retains charges accumulated in a capacitor connected in series with the transistor for a long period of time due to its low off-state current. Is possible.

  The semiconductor layer is expressed by an In-M-Zn-based oxide containing indium, zinc, and M (metal such as aluminum, titanium, gallium, germanium, yttrium, zirconium, lanthanum, cerium, tin, neodymium, or hafnium). It can be a membrane.

  When the metal oxide composing the semiconductor layer is an In-M-Zn-based oxide, the atomic ratio of the metal element of the sputtering target used for forming the In-M-Zn oxide is In ≧ M, Zn It is preferable to satisfy ≧ M. As the atomic ratio of the metal elements of such a sputtering target, In: M: Zn = 1: 1: 1, In: M: Zn = 1: 1: 1.2, In: M: Zn = 3: 1: 2, In: M: Zn = 4: 2: 3, In: M: Zn = 4: 2: 4.1, In: M: Zn = 5: 1: 6, In: M: Zn = 5: 1: 7, In: M: Zn = 5: 1: 8 etc. are preferable. Note that the atomic ratio of the semiconductor layer to be formed includes a variation of plus or minus 40% of the atomic ratio of the metal element contained in the sputtering target.

  The bottom-gate transistor described in this embodiment is preferable because the number of manufacturing steps can be reduced. In addition, by using a metal oxide at this time, the wiring under the semiconductor layer can be formed at a temperature lower than that of polycrystalline silicon, and a material having low heat resistance can be used as an electrode material and a substrate material. Can widen the choice of materials. For example, a glass substrate having an extremely large area can be suitably used.

As the semiconductor layer, a metal oxide film with low carrier density is used. For example, the semiconductor layer has a carrier density of 1 × 10 ¹⁷ / cm ³ or less, preferably 1 × 10 ¹⁵ / cm ³ or less, more preferably 1 × 10 ¹³ / cm ³ or less, more preferably 1 × 10 ¹¹ / cm 3. ³ or less, more preferably less than 1 × ^{10 10} / cm ^3, it is possible to use a 1 × ¹⁰ -9 / cm ³ metal oxide or more carrier density. Such metal oxides are referred to as high purity intrinsic or substantially high purity intrinsic metal oxides. Accordingly, it can be said that the metal oxide has stable characteristics because the impurity concentration is low and the density of defect states is low.

  Note that the composition is not limited thereto, and a transistor having an appropriate composition may be used depending on required semiconductor characteristics and electrical characteristics (field-effect mobility, threshold voltage, and the like) of the transistor. In addition, in order to obtain the required semiconductor characteristics of the transistor, it is preferable that the semiconductor layer have appropriate carrier density, impurity concentration, defect density, atomic ratio of metal element to oxygen, interatomic distance, density, and the like. .

If the metal oxide constituting the semiconductor layer contains silicon or carbon which is one of the Group 14 elements, oxygen vacancies increase in the semiconductor layer and become n-type. Therefore, the concentration of silicon or carbon in the semiconductor layer (concentration obtained by secondary ion mass spectrometry) is 2 × 10 ¹⁸ atoms / cm ³ or less, preferably 2 × 10 ¹⁷ atoms / cm ³ or less.

In addition, when an alkali metal and an alkaline earth metal are combined with a metal oxide, carriers may be generated, which may increase the off-state current of the transistor. Therefore, the concentration of alkali metal or alkaline earth metal obtained by secondary ion mass spectrometry in the semiconductor layer is set to 1 × 10 ¹⁸ atoms / cm ³ or less, preferably 2 × 10 ¹⁶ atoms / cm ³ or less.

In addition, when nitrogen is contained in the metal oxide constituting the semiconductor layer, electrons as carriers are generated, the carrier density is increased, and the n-type is easily obtained. As a result, a transistor using a metal oxide containing nitrogen is likely to be normally on. For this reason, it is preferable that the nitrogen concentration obtained by secondary ion mass spectrometry in the semiconductor layer is 5 × 10 ¹⁸ atoms / cm ³ or less.

  The semiconductor layer may have a non-single crystal structure, for example. The non-single-crystal structure includes, for example, a CAAC-OS (C-Axis Crystalline Oxide Semiconductor Semiconductor) having a crystal oriented in the c-axis, or a C-Axis Aligned and A-B-Plane Annealed Crystal Oxide Crystal Structure, Includes a microcrystalline structure or an amorphous structure. In the non-single-crystal structure, the amorphous structure has the highest density of defect states, and the CAAC-OS has the lowest density of defect states.

  An amorphous metal oxide film has, for example, disordered atomic arrangement and no crystal component. Alternatively, the oxide film having an amorphous structure has, for example, a completely amorphous structure and does not have a crystal part.

  Note that the semiconductor layer may be a mixed film including two or more of an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CAAC-OS region, and a single crystal structure region. Good. For example, the mixed film may have a single-layer structure or a stacked structure including any two or more of the above-described regions.

<Configuration of CAC-OS>
A structure of a CAC (Cloud-Aligned Composite) -OS that can be used for the transistor disclosed in one embodiment of the present invention is described below.

  In this specification and the like, a metal oxide is a metal oxide in a broad expression. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), oxide semiconductors (also referred to as oxide semiconductors or simply OS), and the like. For example, when a metal oxide is used for an active layer of a transistor, the metal oxide may be referred to as an oxide semiconductor. That is, in the case of describing as an OS FET, it can be translated into a transistor including a metal oxide or an oxide semiconductor.

  In this specification, in the case where a metal oxide region in which a region having a conductor function and a region having a dielectric function are mixed and the entire metal oxide functions as a semiconductor, a CAC (Cloud-Aligned Composite) − It is defined as OS (Oxide Semiconductor) or CAC-metal oxide.

  In other words, the CAC-OS is one structure of a material in which an element included in an oxide semiconductor is unevenly distributed with a size of 0.5 nm to 10 nm, preferably 0.5 nm to 3 nm, or the vicinity thereof. . Note that in the following, in an oxide semiconductor, one or more elements are unevenly distributed, and a region including the element has a size of 0.5 nm to 10 nm, preferably 0.5 nm to 3 nm, or the vicinity thereof. The state mixed with is also referred to as mosaic or patch.

  The physical characteristics of a region where a specific element is unevenly distributed are determined by the properties of the element. For example, a region in which elements that tend to become insulators are relatively uneven among the elements constituting the metal oxide is a dielectric region. On the other hand, a region in which elements that tend to be conductors are relatively uneven among the elements constituting the metal oxide is a conductor region. Further, the conductor region and the dielectric region are mixed in a mosaic shape, so that the material functions as a semiconductor.

  That is, the metal oxide in one embodiment of the present invention is a kind of a matrix composite or a metal matrix composite in which materials having different physical properties are mixed.

  Note that the oxide semiconductor preferably contains at least indium. In particular, it is preferable to contain indium and zinc. In addition to them, element M (M is gallium, aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum. , One or more selected from tungsten, magnesium, or the like) may be included.

For example, a CAC-OS in In-Ga-Zn oxide (In-Ga-Zn oxide among CAC-OSs may be referred to as CAC-IGZO in particular) is an indium oxide (hereinafter referred to as InO). _X1 (X1 is greater real than 0) and.), or indium zinc oxide _{(hereinafter, in X2 Zn Y2 O Z2 (} X2, Y2, and Z2 is larger real than 0) and a.), gallium An oxide (hereinafter referred to as GaO _X3 (X3 is a real number greater than 0)) or a gallium zinc oxide (hereinafter referred to as Ga _X4 Zn _Y4 O _Z4 (where X4, Y4, and Z4 are greater than 0)) to.) and the like, the material becomes mosaic by separate into, mosaic _{InO X1,} or _in X2 _Zn Y2 _{O Z2} is configured uniformly distributed in the film (hereinafter, cloud Also referred to.) A.

That, CAC-OS includes a region _{GaO X3} is the main _component, In _{X2 Zn} Y2 _{O Z2,} or _{InO X1} there is a region which is a main component, a composite oxide semiconductor having a structure that is mixed. Note that in this specification, for example, the first region indicates that the atomic ratio of In to the element M in the first region is larger than the atomic ratio of In to the element M in the second region. It is assumed that the concentration of In is higher than that in the second region.

Note that IGZO is a common name and sometimes refers to one compound of In, Ga, Zn, and O. As a typical example, InGaO ₃ (ZnO) _m1 (m1 is a natural number) or In _{(1 + x0)} Ga _(1-x0) O ₃ (ZnO) _m0 (−1 ≦ x0 ≦ 1, m0 is an arbitrary number) A crystalline compound may be mentioned.

  The crystalline compound has a single crystal structure, a polycrystalline structure, or a CAAC structure. The CAAC structure is a crystal structure in which a plurality of IGZO nanocrystals have c-axis orientation and are connected without being oriented in the ab plane.

  On the other hand, CAC-OS relates to a material structure of an oxide semiconductor. CAC-OS refers to a nanoparticulate region mainly composed of Ga and partly composed of In, in a material configuration containing In, Ga, Zn, and O. Are observed, each of which is randomly dispersed in a mosaic pattern. Therefore, in the CAC-OS, the crystal structure is a secondary element.

  Note that the CAC-OS does not include a stacked structure of two or more kinds of films having different compositions. For example, a structure composed of two layers of a film mainly containing In and a film mainly containing Ga is not included.

Incidentally, a region _{GaO X3} is the main _component, In _{X2 Zn} Y2 _{O Z2,} or the region _{InO X1} is the main component, it may clear boundary can not be observed.

  Instead of gallium, selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, etc. In the case where one or a plurality of types are included, in the CAC-OS, a nanoparticulate region mainly containing the element is observed in part, and a nanoparticulate region mainly containing In is partly observed. Are observed, each of which is randomly dispersed in a mosaic pattern.

<Analysis of CAC-OS>
Subsequently, the results of measurement of an oxide semiconductor film formed on a substrate using various measurement methods will be described.

<< Sample structure and production method >>
In the following, nine samples according to one embodiment of the present invention are described. Each sample is manufactured under different conditions for the substrate temperature and the oxygen gas flow rate when the oxide semiconductor film is formed. Note that the sample has a structure including a substrate and an oxide semiconductor over the substrate.

  A method for manufacturing each sample will be described.

  First, a glass substrate is used as the substrate. Subsequently, an In—Ga—Zn oxide with a thickness of 100 nm is formed as an oxide semiconductor over the glass substrate with a sputtering apparatus. The deposition conditions are such that the pressure in the chamber is 0.6 Pa and an oxide target (In: Ga: Zn = 4: 2: 4.1 [atomic ratio]) is used as the target. In addition, 2500 W AC power is supplied to the oxide target installed in the sputtering apparatus.

  Note that as a condition for forming the oxide, the substrate temperature was set to a temperature at which the substrate was not intentionally heated (hereinafter also referred to as room temperature or RT), 130 ° C., or 170 ° C. In addition, nine samples are manufactured by setting the flow rate ratio of oxygen gas to the mixed gas of Ar and oxygen (hereinafter also referred to as oxygen gas flow rate ratio) to 10%, 30%, or 100%.

≪Analysis by X-ray diffraction≫
In this item, the results of X-ray diffraction (XRD) measurement on nine samples will be described. Note that Bruker D8 ADVANCE was used as the XRD apparatus. The condition is that the scanning range is 15 deg. In θ / 2θ scanning by the out-of-plane method. To 50 deg. , The step width is 0.02 deg. The scanning speed is 3.0 deg. / Min.

  FIG. 13 shows the results of measuring the XRD spectrum using the out-of-plane method. In FIG. 13, the upper part shows the measurement result for the sample whose substrate temperature condition during film formation is 170 ° C., the middle part shows the measurement result for the sample whose substrate temperature condition during film formation is 130 ° C., and the lower part shows the measurement result during film formation. The substrate temperature condition of R.R. T.A. The measurement result in the sample is shown. The left column shows the measurement results for the sample with an oxygen gas flow ratio of 10%, the center column shows the measurement results for a sample with an oxygen gas flow ratio of 30%, and the right column shows the oxygen gas flow rate. The measurement result in the sample whose ratio condition is 100% is shown.

  In the XRD spectrum shown in FIG. 13, the peak intensity in the vicinity of 2θ = 31 ° is increased by increasing the substrate temperature during film formation or increasing the ratio of the oxygen gas flow rate ratio during film formation. Note that the peak near 2θ = 31 ° is a crystalline IGZO compound (also referred to as CAAC (c-axis aligned crystalline) -IGZO) oriented in the c-axis with respect to a surface to be formed or an upper surface substantially perpendicular to the surface. Is known to originate from

  Further, in the XRD spectrum shown in FIG. 13, a clear peak did not appear as the substrate temperature during film formation was lower or the oxygen gas flow rate ratio was smaller. Therefore, it can be seen that the sample having a low substrate temperature during film formation or a small oxygen gas flow ratio does not show orientation in the ab plane direction and c-axis direction of the measurement region.

≪Analysis with electron microscope≫
In this item, the substrate temperature R.D. T.A. The results of observation and analysis of a sample prepared at an oxygen gas flow rate ratio of 10% by HAADF (High-Angle Angular Dark Field) -STEM (Scanning Transmission Electron Microscope) are described below (hereinafter acquired by HAADF-STEM). The image is also called a TEM image.)

  The results of image analysis of a planar image (hereinafter also referred to as a planar TEM image) acquired by HAADF-STEM and a cross-sectional image (hereinafter also referred to as a sectional TEM image) will be described. The TEM image was observed using a spherical aberration correction function. The HAADF-STEM image was taken by irradiating an electron beam with an acceleration voltage of 200 kV and a beam diameter of about 0.1 nmφ using an atomic resolution analytical electron microscope JEM-ARM200F manufactured by JEOL Ltd.

  FIG. 14A shows the substrate temperature R.P. T.A. And a planar TEM image of a sample prepared at an oxygen gas flow rate ratio of 10%. FIG. 14B shows the substrate temperature R.D. T.A. And a cross-sectional TEM image of a sample manufactured at an oxygen gas flow rate ratio of 10%.

≪Analysis of electron diffraction pattern≫
In this item, the substrate temperature R.D. T.A. A result of acquiring an electron beam diffraction pattern by irradiating an electron beam having a probe diameter of 1 nm (also referred to as a nanobeam electron beam) to a sample manufactured at an oxygen gas flow rate ratio of 10% will be described.

  As shown in FIG. 14A, the substrate temperature R.D. T.A. In a planar TEM image of a sample manufactured at an oxygen gas flow rate ratio of 10%, electron beam diffraction patterns indicated by black spots a1, black spots a2, black spots a3, black spots a4, and black spots a5 are observed. The observation of the electron beam diffraction pattern is performed while moving at a constant speed from the 0 second position to the 35 second position while irradiating the electron beam. FIG. 14C shows the result of black point a1, FIG. 14D shows the result of black point a2, FIG. 14E shows the result of black point a3, FIG. 14F shows the result of black point a4, and FIG. As shown in FIG.

  From FIG. 14C, FIG. 14D, FIG. 14E, FIG. 14F, and FIG. 14G, it is possible to observe a high luminance region like a circle (in a ring shape). A plurality of spots can be observed in the ring-shaped region.

  Further, as shown in FIG. 14B, the substrate temperature R.D. T.A. In the cross-sectional TEM image of the sample prepared at an oxygen gas flow rate ratio of 10%, the electron beam diffraction patterns indicated by black spots b1, black spots b2, black spots b3, black spots b4, and black spots b5 are observed. FIG. 14H shows the result of black point b1, FIG. 14I shows the result of black point b2, FIG. 14J shows the result of black point b3, FIG. 14K shows the result of black point b4, and FIG. As shown in FIG.

  From FIG. 14 (H), FIG. 14 (I), FIG. 14 (J), FIG. 14 (K), and FIG. A plurality of spots can be observed in the ring-shaped region.

Here, for example, when an electron beam with a probe diameter of 300 nm is incident on a CAAC-OS having an InGaZnO ₄ crystal in parallel to the sample surface, spots resulting from the (009) plane of the InGaZnO ₄ crystal are included. A diffraction pattern is seen. That is, it can be seen that the CAAC-OS has c-axis orientation and the c-axis is oriented in a direction substantially perpendicular to the formation surface or the top surface. On the other hand, when an electron beam with a probe diameter of 300 nm is incident on the same sample perpendicularly to the sample surface, a ring-shaped diffraction pattern is confirmed. That is, in the CAAC-OS, the a-axis and the b-axis do not have orientation.

  Further, when electron beam diffraction using an electron beam with a large probe diameter (for example, 50 nm or more) is performed on an oxide semiconductor having microcrystals (hereinafter referred to as nc-OS), a halo pattern is obtained. A simple diffraction pattern is observed. Further, when nanobeam electron diffraction is performed on the nc-OS using an electron beam with a small probe diameter (for example, less than 50 nm), bright spots (spots) are observed. Further, when nanobeam electron diffraction is performed on the nc-OS, a region with high luminance may be observed so as to draw a circle (in a ring shape). In addition, a plurality of bright spots may be observed in the ring-shaped region.

  Substrate temperature R.D. T.A. The electron beam diffraction pattern of a sample manufactured at an oxygen gas flow rate ratio of 10% has a ring-like high luminance region and a plurality of bright spots in the ring region. Therefore, the substrate temperature R.D. T.A. And the sample manufactured with an oxygen gas flow rate ratio of 10% has an electron diffraction pattern of nc-OS, and has no orientation in the plane direction and the cross-sectional direction.

  As described above, an oxide semiconductor with a low substrate temperature or a low oxygen gas flow ratio during film formation has properties that are clearly different from those of an amorphous oxide semiconductor film and a single crystal oxide semiconductor film. Can be estimated.

≪Elemental analysis≫
In this item, by using energy dispersive X-ray spectroscopy (EDX) and obtaining and evaluating EDX mapping, the substrate temperature R.D. T.A. The results of elemental analysis of a sample manufactured at an oxygen gas flow rate ratio of 10% will be described. For EDX measurement, an energy dispersive X-ray analyzer JED-2300T manufactured by JEOL Ltd. is used as an element analyzer. A Si drift detector is used to detect X-rays emitted from the sample.

  In the EDX measurement, each point in the analysis target region of the sample is irradiated with an electron beam, and the characteristic X-ray energy and the number of occurrences of the sample generated thereby are measured to obtain an EDX spectrum corresponding to each point. In this embodiment, the peak of the EDX spectrum at each point is represented by the electron transition from the In atom to the L shell, the electron transition from the Ga atom to the K shell, the electron transition from the Zn atom to the K shell, and the K shell from the O atom. And the ratio of each atom at each point is calculated. By performing this for the analysis target region of the sample, EDX mapping showing the distribution of the ratio of each atom can be obtained.

  FIG. 15 shows the substrate temperature R.D. T.A. The EDX mapping in the cross section of the sample produced by oxygen gas flow rate ratio 10% is shown. FIG. 15A is an EDX mapping of Ga atoms (the ratio of Ga atoms to all atoms is in the range of 1.18 to 18.64 [atomic%]). FIG. 15B is EDX mapping of In atoms (the ratio of In atoms to all atoms is in the range of 9.28 to 33.74 [atomic%]). FIG. 15C is an EDX mapping of Zn atoms (the ratio of Zn atoms to all atoms is in the range of 6.69 to 24.99 [atomic%]). 15A, 15B, and 15C show the substrate temperature R.D. during film formation. T.A. In the cross section of the sample manufactured at an oxygen gas flow rate ratio of 10%, the region in the same range is shown. Note that the EDX mapping shows the ratio of elements in light and dark so that the more measurement elements in the range, the brighter the brightness, and the darker the measurement elements. Further, the magnification of EDX mapping shown in FIG. 15 is 7.2 million times.

  In the EDX mapping shown in FIGS. 15A, 15B, and 15C, a relative light / dark distribution is seen in the image, and the substrate temperature R.D. T.A. In the sample prepared at an oxygen gas flow rate ratio of 10%, it can be confirmed that each atom exists in a distributed manner. Here, attention is focused on a range surrounded by a solid line and a range surrounded by a broken line in FIGS. 15A, 15B, and 15C.

  In FIG. 15A, the range surrounded by the solid line includes many relatively dark regions, and the range surrounded by the broken line includes many relatively bright regions. In FIG. 15B, a range surrounded by a solid line includes many relatively bright areas, and a range surrounded by a broken line includes many relatively dark areas.

That is, the range surrounded by the solid line is a region having a relatively large number of In atoms, and the range surrounded by a broken line is a region having a relatively small number of In atoms. Here, in FIG. 15C, in the range surrounded by the solid line, the right side is a relatively bright region and the left side is a relatively dark region. Therefore, the range enclosed by the solid line is a region mainly composed of In _X2 Zn _Y2 O _Z2 or InO _X1 .

A range surrounded by a solid line is a region with relatively few Ga atoms, and a range surrounded by a broken line is a region with relatively many Ga atoms. In FIG. 15C, in the range surrounded by the broken line, the upper left region is a relatively bright region, and the lower right region is a relatively dark region. Therefore, the range surrounded by the broken line is a region whose main component is GaO _X3 , Ga _X4 Zn _Y4 O _Z4 , or the like.

15A, 15B, and 15C, the distribution of In atoms is relatively more uniform than Ga atoms, and InO _X1 is the main component. The regions appear to be connected to each other through a region mainly composed of In _X2 Zn _Y2 O _Z2 . As described above, the region mainly composed of In _X2 Zn _Y2 O _Z2 or InO _X1 is formed in a cloud shape.

Thus, the region which is the main component such as _{GaO X3, In X2 Zn Y2 O} Z2, or _{InO X1} there is a region which is a main component, ubiquitously, an In-Ga-Zn oxide having a mixed to have the structure Things can be referred to as CAC-OS.

  The crystal structure in the CAC-OS has an nc structure. The nc structure possessed by CAC-OS has several bright spots (spots) in addition to bright spots (spots) caused by IGZO including single crystal, polycrystal, or CAAC structure in an electron diffraction pattern. Have. Alternatively, in addition to several bright spots (spots), a crystal structure is defined as a region having a high brightness in a ring shape.

Further, FIG. 15 (A), the FIG. 15 (B), the and 15 from (C), such as _{GaO X3} is the main component area, and _In X2 _Zn Y2 _{O Z2,} or _{InO X1} is a region which is the main component The size is observed from 0.5 nm to 10 nm, or from 1 nm to 3 nm. Preferably, in EDX mapping, the diameter of a region in which each element is a main component is 1 nm or more and 2 nm or less.

As described above, the CAC-OS has a structure different from that of the IGZO compound in which the metal elements are uniformly distributed and has properties different from those of the IGZO compound. That is, in the CAC-OS, a region in which GaO _X3 or the like is a main component and a region in which In _X2 Zn _Y2 O _Z2 or InO _X1 is a main component are phase-separated from each other, and a region in which each element is a main component. Has a mosaic structure.

Here, the region containing In _X2 Zn _Y2 O _Z2 or InO _X1 as a main component is a region having higher conductivity than a region containing GaO _X3 or the like as a main component. _That, In _{X2 Zn} Y2 _{O Z2,} or _{InO X1} is a region which is a main component, by carriers flow, expressed the conductivity of the oxide semiconductor. Accordingly, a region where In _X2 Zn _Y2 O _Z2 or InO _X1 is a main component is distributed in a cloud shape in the oxide semiconductor, whereby high field-effect mobility (μ) can be realized.

On the other hand, areas such as _{GaO X3} is the main _component, In _{X2 Zn} Y2 _{O Z2,} or _{InO X1} is compared to region which is a main component, has a high area insulation. That is, a region containing GaO _X3 or the like as a main component is distributed in the oxide semiconductor, whereby leakage current can be suppressed and good switching operation can be realized.

Therefore, when CAC-OS is used for a semiconductor element, the insulating property caused by GaO _{X3 and the} like and the conductivity caused by In _X2 Zn _Y2 O _Z2 or InO _X1 act complementarily, thereby increasing the An on-current (I _on ) and high field effect mobility (μ) can be realized.

  In addition, a semiconductor element using a CAC-OS has high reliability. Accordingly, the CAC-OS is optimal for various semiconductor devices including a display.

  In addition, a transistor including a CAC-OS in a semiconductor layer has high field-effect mobility and high driving capability; therefore, the transistor can be used for a driver circuit, typically a gate line driver circuit that generates a gate signal. A display device with a narrow frame width (also referred to as a narrow frame) can be provided. In addition, by using the transistor for a signal line driver circuit that supplies a signal from a signal line included in the display device (particularly, a demultiplexer connected to an output terminal of a shift register included in the signal line driver circuit), display is performed. A display device with a small number of wirings connected to the device can be provided.

  In addition, a transistor having a CAC-OS in a semiconductor layer does not require a laser crystallization step unlike a transistor using a low-temperature polysilicon. For this reason, even in a display device using a large-area substrate, the manufacturing cost can be reduced. Furthermore, in high-resolution displays such as ultra high-definition (“4K resolution”, “4K2K”, “4K”) and super high-definition (“8K resolution”, “8K4K”, “8K”), and in large display devices, semiconductors A transistor having a CAC-OS in the layer is preferably used for a driver circuit and a display portion because writing in a short time is possible and display defects can be reduced.

  Alternatively, silicon may be used for a semiconductor in which a channel of a transistor is formed. Although amorphous silicon may be used as silicon, it is particularly preferable to use silicon having crystallinity. For example, microcrystalline silicon, polycrystalline silicon, single crystal silicon, or the like is preferably used. In particular, polycrystalline silicon can be formed at a lower temperature than single crystal silicon, and has higher field effect mobility and higher reliability than amorphous silicon.

  The bottom-gate transistor described in this embodiment is preferable because the number of manufacturing steps can be reduced. At this time, since amorphous silicon can be used at a lower temperature than polycrystalline silicon, it is possible to use a material having low heat resistance as the electrode material and substrate material for the wiring below the semiconductor layer. Can widen the choice of materials. For example, a glass substrate having an extremely large area can be suitably used. On the other hand, a top-gate transistor is preferable because an impurity region can be easily formed in a self-aligning manner and variation in characteristics can be reduced. At this time, it is particularly suitable when polycrystalline silicon, single crystal silicon, or the like is used.

  This embodiment can be implemented in appropriate combination with at least part of the other embodiments described in this specification.

(Embodiment 5)
FIG. 16 illustrates specific examples of electronic devices that can be used for a portable terminal including the display device according to one embodiment of the present invention. Each of the electronic devices in FIGS. 16A to 16F has a display surface with respect to a curved surface or a plurality of directions. By using the display device described in Embodiment Mode 1, a viewing angle can be controlled and a comfortable display in which display quality is not deteriorated can be obtained.

  In Embodiment 1, FIGS. 16A and 16C illustrate examples of electronic devices in which viewing angle control is performed on the inner angles of two housings, FIGS. In (E) and (F), viewing angle control can be performed toward an external angle exceeding 180 degrees.

  FIG. 16A illustrates a portable game machine including a housing 5001, a housing 5002, a display device 5003 according to one embodiment of the present invention, a microphone 5005, a speaker 5006, operation keys 5007, a stylus 5008, and the like. By using the display device 5003 according to one embodiment of the present invention for a portable game machine, an image with high display quality can be displayed on the display device 5003 without being influenced by the intensity of external light in a use environment. Power can also be reduced.

  FIG. 16B illustrates a wristwatch-type portable terminal including a housing 5201, a display device 5202 according to one embodiment of the present invention, a belt 5203, an optical sensor 5204, a switch 5205, and the like. By using the display device 5202 according to one embodiment of the present invention for a wristwatch-type mobile terminal, an image with high display quality can be displayed on the display device 5202 without being influenced by the intensity of external light in the usage environment. Power consumption can also be suppressed.

  FIG. 16C illustrates a tablet personal computer including a housing 5301, a housing 5302, a display device 5303 according to one embodiment of the present invention, an optical sensor 5304, an optical sensor 5305, a switch 5306, and the like. The display device 5303 is supported by a housing 5301 and a housing 5302. Since the display device 5303 is formed using a flexible substrate, the display device 5303 has a function of flexibly bending the shape. By changing the angle between the housing 5301 and the housing 5302 at the hinges 5307 and 5308, the display device 5303 can be folded so that the housing 5301 and the housing 5302 overlap with each other. Although not shown, an open / close sensor may be incorporated, and the change in the angle may be used as information on the use condition in the display device 5303. By using the display device 5303 according to one embodiment of the present invention for a tablet personal computer, an image with high display quality can be displayed on the display device 5303 without being influenced by the intensity of external light in the usage environment. Power consumption can also be suppressed.

  FIG. 16D illustrates a periphery of a driver's seat in a moving object such as an automobile, which includes a handle 5801, a pillar 5802, a door 5803, a windshield 5804, a display device 5805 according to one embodiment of the present invention, and the like. Since the display device 5805 is formed using a flexible substrate, the display device 5805 has a function of flexibly bending the shape. Therefore, the present invention can be applied to an instrument panel that displays instruments in a dashboard of a car having a flat surface or a different curved surface. By using the display device 5805 according to one embodiment of the present invention for an instrument panel of an automobile, an image with high display quality can be displayed on the display device 5805 without being influenced by the intensity of external light in a use environment. Power consumption can also be suppressed.

  FIG. 16E illustrates a wristwatch-type portable terminal including a housing 5701 having a curved surface, a display device 5702 according to one embodiment of the present invention, and the like. By using a flexible substrate for the display device 5702 according to one embodiment of the present invention, the display device 5702 can be supported by a housing 5701 having a curved surface, and is flexible, light, and easy to use. A terminal can be provided. Then, by using the display device 5702 according to one embodiment of the present invention for a wristwatch-type mobile terminal, an image with high display quality can be displayed on the display device 5702 without being influenced by the intensity of external light in the usage environment. And power consumption can be reduced.

  FIG. 16F illustrates a cellular phone. A housing 5901 having a curved surface includes a display device 5902, a microphone 5907, a speaker 5904, a camera 5903, an external connection portion 5906, and an operation button 5905 according to one embodiment of the present invention. Is provided. By using the display device 5902 according to one embodiment of the present invention for a mobile phone, an image with high display quality can be displayed on the display device 5902 without depending on the intensity of external light in the usage environment, and power consumption can be reduced. Can be suppressed.

  This embodiment can be implemented in appropriate combination with any of the other embodiments.

A1 pixel A2 pixel AF1 alignment film AF2 alignment film ANO wiring B1 display surface B2 display direction B11 display surface C1 display surface C2 display direction C11 display surface CSCOM wiring CF1 colored layer G1 scanning line G2 scanning line R1 incident direction R2 direction R3 incident direction R4 Direction R30 Angle R45 Angle R45C Display direction R90 Angle R90B Display direction S1 Signal line S2 Signal line 10 Electronic device 11 Case 12 Case 13 Hinge 14 Display device 30 View angle 45 View angle 51 Display region 52 Display region 53 Display region 61 Guide Display 62 Direction indication 100 Pixel 101 Substrate 102 Substrate 103 Pixel circuit 110 Pixel circuit 111 Transistor 112 Capacitor element 113 Display element 114 Pixel electrode 115 Common electrode 116 Liquid crystal layer 120 Pixel circuit 121 Transistor 122 Transistor 123 Capacitor element 124 Field light emitting layer 125 Pixel electrode 126 Common electrode 127 Display element 130 Contact 131 Contact 132 Contact 134 Contact 150 Open region 150H Open region 160 Open region 160H Open region 200 Layer 201a Conductive layer 201b Conductive layer 201c Conductive layer 201d Conductive layer 201e Conductive layer 202a Oxide semiconductor layer 202b Oxide semiconductor layer 203a Conductive layer 203b Conductive layer 203d Conductive layer 203e Conductive layer 204a Conductive layer 208 Reflective electrode 208a Conductive layer 208b Conductive layer 208c Conductive layer 210 Insulating layer 211 Insulating layer 212 Insulating layer 213 Insulating layer 215 Insulating Layer 216 Insulating layer 218 Insulating layer 280 Reflective electrode 300 Display device 311b Electrode 351 Substrate 360 Display element 361 Substrate 362 Display unit 364 Circuit unit 365 Wiring 366 Circuit unit 367 Arrangement 368 touch sensor 372 FPC
373 IC
400 CPU
410 CPU
411 Display controller 412 Memory 413 Camera 413a Camera 413b Camera 414 GPS communication module 415 Gyro sensor 416 Acceleration sensor 417 Optical sensor 418 Touch sensor 419 Speaker 420 Microphone 421 Battery 430 Display device 431 Reflective liquid crystal display device 432 Light emitting display device 900 Electronic device 901 Case 901a Case 901b Case 902 Display unit 903 Hinge 910 Electronic device 911a Case 911b Case 912 Display unit 913 Hinge 914a Operation button 914b Operation button 915 Cartridge 920 Electronic device 921a Case 921b Case 922 Display unit 923 Hinge 930 Navigation system 5001 Case 5002 Case 5003 Display device 5005 Microphone 5006 Speaker 5007 Key 5008 Stylus 5201 Housing 5202 Display device 5203 Belt 5204 Optical sensor 5205 Switch 5301 Housing 5302 Housing 5303 Display device 5304 Optical sensor 5305 Optical sensor 5306 Switch 5307 Hinge 5701 Housing 5702 Display device 5801 Handle 5802 Pillar 5803 Door 5804 Windshield 5805 Display device 5901 Housing 5902 Display device 5903 Camera 5904 Speaker 5905 Button 5906 External connection portion 5907 Microphone 8000 Display module 8001 Upper cover 8002 Lower cover 8005 FPC
8006 Display panel 8009 Frame 8010 Printed circuit board 8011 Battery 8015 Light emitting unit 8016 Light receiving unit 8017a Light guide unit 8017b Light guide unit 8018 Light

Claims (12)

Having a first surface, a second surface, and a third surface;
The first surface and the third surface are continuous via the second surface,
Between the first surface and the third surface, the second surface having a curvature,
The first surface has a first display area,
The second surface has a second display area,
The third surface has a third display area,
A fourth display area is configured using the first display area and the second display area,
A fifth display area is configured using the second display area and the third display area,
A display device, wherein a sixth display area is configured using the first display area, the second display area, and the third display area. In claim 1,
The first display area, the second display area, and the third display area have a plurality of pixels.
The pixel has a first display element and a second display element,
The first display element has a reflective electrode for reflecting visible light included in external light,
The reflective electrode has an opening region or a notch region,
The second display element has a function of transmitting visible light from the opening region or the cutout region,
The display device having a function in which the first display element and the second display element display different gradations. In Claim 1, It has the 1st viewing angle in the 1st surface, and the 2nd viewing angle in the 3rd surface,
A display device comprising a region where the first viewing angle and the second viewing angle overlap. In any one of Claim 1 thru | or 3,
The second display element includes a first region having the same area as the opening region or the notch region, and a second region having a larger area than the opening region or the notch region,
The second area has a function of widening the viewing angle of the second display element in the first display area and the viewing angle of the second display element in the third display area,
The display device according to claim 1, wherein a viewing angle of the second display element in the first display region has a region overlapping with a viewing angle of the second display element in the third display region. In any one of Claims 1 thru | or 4,
In each of the first display area and the third display area, the second display element includes a first area overlapping with the opening area or the notch area, and overlapping with the opening area or the notch area. A second region that must not be
The display device according to claim 1, wherein an area of the second region in the first display region is different from an area of the second region in the third display region. In any one of Claims 1 thru | or 5,
The display device in which the first display element is a reflective liquid crystal element. In any one of Claims 1 thru | or 5,
The display device, wherein the second display element is a light emitting element.   The display device according to claim 1 includes a transistor, and the transistor includes a metal oxide in a semiconductor layer. In claim 8,
The display device, wherein the transistor has a back gate. The display device according to any one of claims 1 to 9,
A display device having a function of displaying an image by one or both of first light reflected by the first display element and second light emitted by the second display element. A display device according to any one of claims 1 to 10,
A touch sensor;
A display module comprising: A display device according to any one of claims 1 to 10, or a display module according to claim 11,
CPU and battery,
An electronic device comprising: